WO1998045882A1 - Oscillateur quantique a semi-conducteur - Google Patents

Oscillateur quantique a semi-conducteur Download PDF

Info

Publication number
WO1998045882A1
WO1998045882A1 PCT/CN1998/000049 CN9800049W WO9845882A1 WO 1998045882 A1 WO1998045882 A1 WO 1998045882A1 CN 9800049 W CN9800049 W CN 9800049W WO 9845882 A1 WO9845882 A1 WO 9845882A1
Authority
WO
WIPO (PCT)
Prior art keywords
region
band
oscillation
tunneling
semiconductor
Prior art date
Application number
PCT/CN1998/000049
Other languages
English (en)
French (fr)
Inventor
Binghui Li
Original Assignee
Binghui Li
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=5171385&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO1998045882(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Binghui Li filed Critical Binghui Li
Priority to EP98910573A priority Critical patent/EP1009034A4/en
Priority to US09/402,709 priority patent/US6472683B1/en
Priority to JP54220998A priority patent/JP2001522527A/ja
Priority to AU64936/98A priority patent/AU6493698A/en
Publication of WO1998045882A1 publication Critical patent/WO1998045882A1/zh

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/04—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
    • H01L29/861—Diodes
    • H01L29/88—Tunnel-effect diodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers

Definitions

  • the invention relates to a quantum effect semiconductor device, and more particularly to a semiconductor quantum oscillator device.
  • This type of device emits electromagnetic radiation in response to an applied electric field.
  • the frequency of the emitted electromagnetic radiation is between the high end of the microwave and the low end of the infrared. range.
  • the basic theoretical consideration related to the present invention is the behavior of the electrons in the crystal under an applied uniform steady-state electric field. More than 60 years ago, the work of F. Bloch (see F. Bloch, Z. Phys. 52, 555 (1928)) and C. Zener (C. Zener, Proc. R. Soc. 145, 523 (1934)) showed If the electrons in the crystal are regarded as a wave packet composed of Bloch functions, the electrons in a certain energy band in the crystal will be excited to a higher energy band in response to the applied electric field without being affected by scattering. Previously, periodic motion was performed in wave vector space under the combined effect of the lattice periodic potential and the applied external electric field.
  • the frequency of this periodic motion is eFa / h, where e is the electronic charge, F is the electric field strength, a is the lattice constant, and h is the Planck constant.
  • the periodic motion of an electron in wave vector space (k-space) means that it also does periodic motion in real space.
  • This periodic motion of electrons is generally called Bloch oscillation (or Zener oscillation), and it is also called Zener-Bloch oscillation or Bloch-Zener oscillation.
  • the Bloch oscillation is caused by the ballistically accelerated electrons being reflected by the Bragg at the boundary of the Brillouin zone and moving in the Brillouin zone.
  • Bloch oscillations correspond to quantum beats generated by interference between states.
  • G. Bastard and R. Ferreira entitled "Vanier in a biased semiconductor superlattice- A paper (Spectroscopy of Semiconductor Microstructures, NATO AS I Series (Plenum, New York, 1989), p. 333).
  • the electrons are not excited to a higher energy band (inter-band tunneling or Zenner tunneling) at least before undergoing a complete oscillation cycle, and are not subject to scattering.
  • inter-band tunneling without considering the influence of phonons, the upper limit of its probability has been strictly proved theoretically based on the one-electron approximation. The results show that electrons can experience multiple oscillations before tunneling into the high energy band Cycle (see A. Nenciu and G. Ninciu, J. Phys. A14, 2817 (1981)). Therefore, inter-band tunneling is not a major limitation to achieve Bloch oscillation.
  • the scattering to which electrons are subjected includes phonon scattering and miscellaneous shield scattering.
  • Bloch oscillations are not observed in normal solids (including semiconductors) (see G. von Plessen and P. Tomas, Phys. Rev. 45, 9185 (1992)).
  • P. Roblin in and MW Muller J. Phys. C: Sol id state Phys. 16 4547 (1983) have studied the characteristics of the electrons that can be used for real Bloch oscillations (known as coherent Zener oscillations in this document). It was found that only quasi-coherent electrons can achieve Bloch oscillations. Quasi-coherent electrons exhibit the characteristics of many classical particles and can be called classical (like) or ballistic electrons.
  • L. Esaki and R. Tsu proposed a semiconductor oscillating device using a semiconductor superlattice structure to implement 1 och oscillation from the perspective of application.
  • the starting point is to use the micro-Brillouin zone of the superlattice to be smaller than the Brillouin zone of the normal lattice to make it easier for electrons to avoid the limitation of scattering under the action of an electric field to achieve periodic motion.
  • the purpose of this application is to obtain a device that can emit high-frequency electromagnetic radiation by using Bloch oscillations of electrons in a superlattice. So far, the device proposed in this patent has not actually been manufactured (see JU. Esaki, in Science and Technology of Mesoscopic Structures, Springer-Verlag, 1992, P. 3).
  • An object of the present invention is to provide a semiconductor quantum oscillator device that realizes loch oscillation based on a new carrier atom (including conduction band electrons and valence band holes).
  • the note proposed by the inventors not only can overcome the high polar phonon scattering that exists in the injection stage which cannot be avoided in the prior art, but can also keep the phase between the injected electrons and the phase between the injected holes consistent.
  • the scattering effect of phonons in semiconductors on the electrons in the full valence band is much smaller than the scattering of the electrons in the valence band or the conduction band in the commonly doped semiconductors. Because for a semiconductor valence band filled with electrons, if the internal electrons are scattered by phonons, then since there is no empty state electron in the band, it is only possible to be scattered into the conduction band. In fact, because there is a forbidden band between the conduction band and the valence band that is much larger than the average thermal motion energy, the probability of this scattering is small.
  • the topmost electron in the filled valence band (wave vector is zero) can be excited to the conduction band by tunneling between the energy bands.
  • electrons and holes that can move freely can be introduced at the top of the conduction band and the valence band, respectively.
  • the valence band top electrons in the full valence band are weakly affected by phonon scattering before the tunneling occurs. Therefore, if we try to make the phonon not participate in the interband tunneling, then the obtained free conduction band Electrons and valence band holes can avoid the influence of phonon scattering.
  • the electrons excited to the conduction band by tunneling are only the electrons located at the top of the valence band, and their wave vectors are close to zero, the wave vectors remain conserved during the tunneling process without phonons. Therefore, if we try to make If the inter-band tunneling occurs only at a local position, the phase of the obtained conduction band electrons and valence band holes will also be consistent.
  • the requirement of phonons to scatter the electrons that make the Moch oscillation is avoided by using the phonon frequency with an oscillation frequency greater than the maximum longitudinal optical (L0) phonon frequency.
  • the electric field strength should be greater than 1000 kVcm-l. This requirement is consistent with the requirement for electric field strength in the case of inter-band tunneling in semiconductors.
  • the thickness, composition and / or stress of each layer can be achieved by the strong electric field.
  • Inter-band tunneling occurs only locally in the entire multilayer structure, and does not require the participation of phonons.
  • the part where the inter-band tunneling occurs in the structure can be used as the injection region of the B 1 och oscillator device, in order to note coherent electrons and holes that are consistent at a position.
  • the present invention provides a practical working quantum oscillator device based on Bloch oscillation.
  • the main working principle is to use the electron-to-empty conduction band at the top of a semiconductor full-valence band that locally occurs in an undoped semiconductor multilayer structure.
  • Inter-band tunneling also known as Zenner tunneling
  • Zenner tunneling with the participation of phonons achieves the injection of coherent electrons and holes in the same phase.
  • the semiconductor quantum oscillator device of the present invention includes a heterostructure composed of a plurality of semiconductor layers and a device for applying a voltage to the semiconductor heterostructure, and is characterized in that:
  • the semiconductor heterostructure includes a tunneling injection region and two carrier oscillation regions-an electron oscillation region and a hole oscillation region, which are directly connected to and located on both sides of the semiconductor implantation region.
  • the voltage applying device applies a voltage between two In each oscillation region, the valence band electrons that cause tunneling and injection into the penetration region pass through the inter-band tunneling to the conduction band, and electrons and holes that do quantum oscillation motion are introduced in the two oscillation regions to generate far-infrared radiation.
  • the semiconductor quantum oscillator device further includes two contact areas and corresponding contact electrodes located on a side where the two carrier oscillation areas are not in contact with the tunneling injection area, and the voltage applying device passes through two The contact electrode applies a voltage to the two carrier oscillation regions.
  • the tunneling injection region and the carrier oscillating region are composed of heterostructures obtained by arranging a plurality of semiconductor epitaxial layers having different forbidden band widths in a specific order.
  • electromagnetic oscillators with a frequency greater than 300 GHz are obtained by using an existing two-terminal and three-terminal semiconductor device.
  • mid-infrared 5-8 ⁇
  • the electromagnetic radiation covers this area of the electromagnetic frequency. Therefore,
  • the semiconductor quantum oscillator device based on Bloch oscillation provided by the present invention will pave the way for making full use of electromagnetic wave resources in this area.
  • FIG. 1 is a schematic structural diagram of a semiconductor quantum oscillator device using phonons to participate in inter-band tunneling to achieve carrier injection according to the present invention.
  • FIG. 2 is a schematic diagram of the current-voltage characteristic curve of the device shown in FIG. 1, which illustrates that a threshold voltage Vc exists corresponding to the start of tunneling between bands.
  • Figure 3 is a band diagram explaining the performance of an inter-band tunneling injection region and carrier oscillation region structure that can be used in the device shown in Figure 1.
  • FIG. 4 is a schematic diagram of the energy bands of the tunneling injection region and the carrier oscillation region shown in FIG. 3 when the applied voltage is a critical voltage.
  • Figures 5-7 are explanatory performance band diagrams of other interband tunneling injection region and carrier oscillation regions structures that can be used in the device shown in Figure 1.
  • Fig. 8 is a band diagram explaining the structure of the structure obtained by slightly changing the structures of the inter-band tunneling injection region and the carrier oscillation region shown in Fig. 3.
  • Figure 9 is an energy band diagram of a device using a superlattice structure as the electronic oscillation region.
  • FIG. 10 is a schematic cross-sectional view of an embodiment of a semiconductor quantum oscillator device of the present invention.
  • FIG. 11 is a current-voltage characteristic curve obtained by actually measuring the embodiment shown in FIG. 10.
  • FIG. 1 is a schematic structural diagram of a semiconductor quantum oscillating device including an inter-band tunneling injection region and a carrier oscillation region according to the present invention.
  • the number 100 in the figure includes the entire device, which specifically includes an inter-band tunneling injection region 102, an electron oscillation region 104 and a hole oscillation region 106, a contact region 108 connected to the electron oscillation region, and a corresponding metal contact electrode 112, and The contact region 110 adjacent to the cavity oscillation region 106 and the corresponding metal contact electrode 114.
  • a device (not shown) for applying a voltage to the semiconductor structure applies a certain voltage to the semiconductor structure through two contact electrodes 112 and 114, and the polarity of the voltage applied by the electrode 112 is positive.
  • This voltage generates a strong electric field in the structure composed of the inter-band tunneling injection region 102 and the two carrier oscillation regions 104 and 106.
  • This electric field first induces inter-band tunneling in the tunnel injection region without the participation of a valence band to the conduction band, thereby generating coherent electrons and holes of the same phase and injecting them into the electron oscillation region 104 and holes Oscillation area 106.
  • the electrons and holes injected into the oscillating region perform quantum oscillations under the combined effect of a strong electric field and the periodic lattice potential of the semiconductor.
  • To generate UHF radiation The emission direction of the radiation is perpendicular to the direction of the applied electric field, and the direction of polarization is parallel to the direction of the electric field.
  • the semiconductor quantum oscillator device of the present invention is very similar to a side-emitting half-two fel tube,
  • a resonant cavity is formed by using a cleavage surface like a semiconductor laser, or other means are used to feed the emitted electromagnetic radiation back into the device, thereby forming a device.
  • the frequency of Bloch oscillation of the carrier in the oscillation region can be determined by the following formula: hK where e is the electronic charge, F is the electric field strength, h is the Planck constant, ⁇ is the diameter of the Brillouin region along the direction of the electric field, and ⁇ is the same as the specific Band structure related factors.
  • e is the electronic charge
  • F is the electric field strength
  • h is the Planck constant
  • ⁇ the diameter of the Brillouin region along the direction of the electric field
  • ⁇ is the same as the specific Band structure related factors.
  • the contact electrodes 112 and 114 in FIG. 1 are the interface between the quantum oscillator device of the present invention and the outside world. Its functions include two aspects. One is that they can apply an external voltage to tunnel the injection region and the carrier between the bands. The oscillating region generates a strong electric field required for the device to work. In addition, the carriers that receive Bloch oscillation motion in the oscillating region receive carriers that no longer remain coherent due to the scattering phase. These carriers are collected by the contact area and corresponding electrodes to form a current at the device port.
  • the requirement for the contact electrode of the quantum oscillator device of the present invention is that the electrode on the side of the electron oscillation region cannot inject non-coherent electrons into the electron oscillation region, and the contact electrode on the side of the hole oscillation region cannot be directed to the air
  • the cavity oscillation area is injected with non-coherent holes. If this requirement is not met, before reaching the strong electric field required for inter-band tunneling, these non-coherent carriers will induce avalanche breakdown under the action of the electric field, making it impossible to obtain the same phase through inter-band tunneling. Coherent carriers.
  • the metal electrode can inject non-coherent carriers into the carrier oscillation region through tunneling, Therefore, the direct contact between the metal electrode and the undoped carrier oscillation region cannot easily meet the above requirements.
  • a dielectric shield layer can be added between the metal electrode and the carrier oscillation region, but it is not practical in practice. Because at this time, although the contact electrode does not inject non-coherent carriers into the carrier oscillating region, an interface state will exist at the interface between the medium and the carrier oscillating region. Under the action of an electric field, these interface states will serve as the center of generation of carriers, and thus incoherent carriers will also be injected into the carrier oscillation region.
  • the semiconductor quantum oscillating device can only work under an applied pulse condition.
  • doped semiconductor contact regions from being added between contact currents, that is, 108 and 110 in FIG. 1, and make the contact between the contact electrode and the contact region an ohmic contact.
  • the doping types of the two contact regions should be different.
  • the doping type of the contact region 112 connected to the electronic oscillation region should be n-type, and the conductivity type of the contact region 114 connected to the hole region should be p-type. .
  • the semiconductor quantum oscillator device of the present invention is very similar to a reverse-biased PI-N diode, and is unique in that its I region is a complex structure composed of a band-to-band tunneling injection region and a carrier oscillation region. structure. It should be particularly pointed out that if the two contact regions are composed of semiconductor layers with the same conductivity type (diode structure is NIN or PI-P), the contact electrode cannot be prevented from injecting non-coherent carriers into the carrier oscillation region. .
  • FIG. 2 is a schematic diagram showing a DC current-voltage characteristic that the semiconductor quantum oscillator device of the present invention should have.
  • the DC current-voltage characteristic curve has an inflection point, and the voltage corresponding to the inflection point is the applied voltage corresponding to the beginning of the inter-band tunneling, which can be called the critical voltage.
  • the critical voltage When the applied voltage is less than the critical voltage, the electrical u of the device is zero, and i ⁇ t should be 20H of the DC characteristic curve.
  • the applied voltage is greater than the critical voltage, coherent electrons and vacancies injected into the carrier oscillation region through interband tunneling
  • the electrons and holes that are no longer in phase due to scattering are collected by the contact electrode to form a straight curve 202.
  • the 202 section of the characteristic curve is drawn as a dotted line in FIG. 2 to reflect this.
  • a space charge effect will occur. The feedback effect of the space charge effect on the band-to-band tunneling will make the actual current-voltage characteristics of the device more complex than the characteristics given in FIG.
  • the core part of the semiconductor quantum oscillator device provided by the present invention is an inter-band tunneling injection region
  • the core part of the device of the present invention is divided into an inter-band tunneling injection region and a carrier oscillation region only for the convenience of description. Since these two regions are directly connected, they can only realize their respective functions together.
  • the following illustrates in the form of an energy band diagram how these two regions are implemented in the quantum oscillator device of the present invention as shown in FIG.
  • These two regions may be formed of a plurality of undoped semiconductor layers by appropriate combinations. By not doping, not only the strong electric fields required for inter-band tunneling and Bloch oscillation can be formed in these two regions, but also the carrier scattering of the loch oscillation can be weakened.
  • the band gaps of the layers shown in the figure are the direct band gaps at the center ⁇ point of the Brillouin region of the layer material.
  • 3 is an energy band diagram of a structure of an inter-band tunneling injection region and a carrier oscillation region of a quantum oscillator device according to the present invention.
  • 301 is a semiconductor layer with a large band gap, such as GaAlAs, as a hole (or electron) electron oscillation region
  • 305 is also a semiconductor layer with a large band gap, such as GaAlAs, as an electron ( Or hole) oscillating region.
  • the minimum band gap of the semiconductor materials of the two layers of 301 and 305 is a direct band gap.
  • the energy band diagram drawn in the figure is a general energy band diagram, and the conduction band edge corresponds to the energy of the electron in the center of the Brillouin region;
  • the conduction band edge in the figure still corresponds to the energy of the central electron in the Brillouin region, although the energy of the conduction band edge at this point is no longer the conduction band.
  • 302 and 304 are two semiconductor layers with a smaller forbidden band width, such as GaAs, and 303 is a semiconductor layer with a larger forbidden band width, such as AlGaAs.
  • Two layers 301 and 303 are used as a constraining layer, and layer 302 pairs electrons and holes to form a quantum potential well-quantum well; two layers 305 and 303 are used as constraining layers, and layer 304 is another quantum well to electrons and holes.
  • quantum wells refer to potential wells with at least one quantized energy level.
  • the width of the well is required to be small, that is, the thickness of the well layer is very thin; at the same time, the depth of the well, that is, the difference between the band edge energy of the confinement layer and the well layer is larger.
  • the minimum band gap of the barrier layer 303 between the two well layers is a direct band gap, but this layer should allow coupling between the quantized energy levels of the two well layers, that is, to form a coupled double quantum Well structure, so that the thickness of this layer is also thin.
  • the three layers 302, 303, and 304 are areas where inter-band tunneling occurs. Under the action of a strong electric field generated by an applied voltage, when the topmost valence band of the quantum well layer 302 and the bottommost conduction band of the rightmost quantum well layer 304 are aligned, the valence band electron levels in the layer 302 are aligned. The coupling with the conduction band electron ⁇ 3 ⁇ 41 in the layer 304 will cause the topmost electron of the full valence band in the layer 302 to tunnel to the conduction band of the layer 304 without the participation of phonons.
  • the forbidden band width of the two barrier layers directly connected to the two well layers is larger than that of the well layers.
  • Inter-band tunneling occurs only in the tunneling region in the entire structure. Electrons that enter the conduction band of the 304 layer through inter-band tunneling will pass through the electron oscillation region 305 through the conduction band tunneling under the action of a strong electric field. Since the electrons entering the electronic oscillation region come from the top of the valence band, that is, the wave vectors are equal to zero, and in the real space, these electrons all come from the same very thin quantum well layer. Therefore, the conduction band electrons thus generated are quasi-classical electrons. Bloch oscillation requires the initial characteristics of the injected electrons.
  • Fig. 4 is a schematic diagram of the energy bands of the tunneling injection region and the carrier oscillation region shown in Fig. 3 when the applied voltage is a critical voltage, and illustrates the situation when inter-band tunneling occurs. According to this figure, a critical electric field Ec can be defined.
  • the electric field generated by the applied voltage in the tunneling injection region and the carrier oscillation region should be larger than the critical electric field so that inter-band tunneling can occur.
  • the applied voltage corresponding to the critical electric field is the critical voltage in FIG. 2.
  • the magnitude of this electric field can be calculated by the following formula:
  • Eg is the band gap width of the two quantum well layers
  • d wl and d 2 are the thicknesses of the two quantum well layers, respectively
  • d b is the thickness of the thin barrier layer between the two quantum wells.
  • InP can also be used as the substrate for InGaAs nP and InGaAs. / Al InAs or InGaAsP / InP heterojunction system, or a GaSb / GaAlSb heterojunction system based on GaSb, AlSb, or ZnTe.
  • epitaxial growth techniques such as molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) are widely known for growing the above heterojunction systems.
  • FIG. 5 is a schematic diagram of the energy band of another structure of the tunneling injection region and the carrier oscillation region of the device.
  • This structure is similar to the structure a shown in FIG. 3, except that the coupled double quantum well in FIG. 3 is replaced with a larger quantum potential well.
  • the thin barrier layer 303 in the middle of the two well layers in FIG. 3 is replaced with a direct band gap material with a smaller forbidden band width as the two well layers, the three layers 302, 303, and 304 constitute a larger width.
  • the structure shown in FIG. 5 can be obtained. Under the action of a strong electric field generated by an applied voltage (for correspondence with FIG.
  • the direction of the electric field is from the layer 503 constituting the electron oscillation region to the layer 501 constituting the hole oscillation region).
  • the leftmost valence band of the quantum well layer 502 When the top energy level is substantially aligned with the energy level at the bottom rightmost conduction band of the layer, the leftmost valence band electron energy level in the layer will be mutually coupled with the rightmost conduction band electron energy. Resonantly tunnel the topmost electron of the leftmost full valence band in ⁇ to the rightmost conduction band of the same layer without the participation of phonons.
  • the conduction band electrons thus generated are also Quasi-classic electronics. These electrons enter the electron oscillation region through the conduction band tunneling, which meets the initial characteristics of Bloch oscillation for the injected electrons. Valence electrons undergo inter-band tunneling while leaving quasi-classical holes on the far left side of the well layer 502. These holes enter the hole oscillation region through tunneling in the valence band, which also satisfies the void injection into the void. Requirements for the initial characteristics of the acupoint.
  • FIG. 6 is an energy band diagram of another structure of a tunneling injection region and a carrier oscillation region of a semiconductor quantum oscillator device of the present invention.
  • the inter-band tunneling injection region and the carrier oscillating region of the device are composed of three semiconductor layers 601, 603, and 602, which form a heterojunction with a ⁇ -type arrangement.
  • the 602 layer there is no special requirement as to whether its minimum band gap is a direct band gap, but it is required to have a small thickness so as to form a quantum potential well for the hole.
  • the direction of the applied electric field is from 603 layers to 601 layers. At this time, the 603 layer constitutes an electronic oscillation region.
  • the leftmost top valence band energy level of the well layer 602 is aligned with the leftmost conduction band bottom of the 603 layer electronic oscillation region ⁇
  • the valence band electrons can be injected into the electron oscillation region through inter-band tunneling.
  • the holes left in the well by valence electron tunneling into the conduction band will be injected into the 601 layer through the inter-band tunneling in the valence band under the action of the electric field.
  • the electrons and holes thus obtained also meet the requirements of the initial characteristics of the carrier for the ⁇ 1 och oscillation.
  • This structure can be realized by using an AlInAs / InP heterojunction system grown on an InP substrate, and the energy band arrangement of the heterojunction system is a ⁇ type.
  • Al InAs has higher energy at the top of the valence band and can be used to form the well layer 602. Accordingly, InP can be used as an electron and hole oscillation region.
  • the band arrangement of a heterojunction system composed of ⁇ -VI compound semiconductors ZnTe and CdSe is also ⁇ -type.
  • ZnTe has a high valence band top energy and can be used to form quantum well layer 602.
  • CdSe can be used to form carrier oscillation Area.
  • FIG. 7 is an energy band diagram of another structure of the inter-band tunneling injection region and the carrier oscillation region of the semiconductor quantum oscillator device of the present invention.
  • the inter-band tunneling injection region and the carrier oscillation region of the semiconductor quantum oscillating device are composed of three layers of three different semiconductor materials, of which three layers 701, 703, and 705 are the same semiconductor material, such as InP; 702 For another material, such as InGaAs, the energy bands of this layer and the heterojunction formed by layers 701 and 703 are arranged as type I, and constitute a quantum well within the limits of these two layers. Therefore, the thickness of this layer is very thin.
  • the 704 layer is a third semiconducting material, such as Al InAs, the energy band of this layer and the heterojunction formed by the two layers 703 and 705 are arranged as ⁇ type, and constitute a quantum for the hole under the limitation of these two layers Well, so the thickness of this layer is also very thin.
  • the depth of the hole quantum well should be smaller than the depth of the hole quantum well composed of 702 layers. It is assumed that the direction of the electric field is from layer 705 to layer 701. At this time, layer 705 constitutes an electron oscillation region and layer 701 constitutes a hole oscillation region.
  • the three layers 702, 703, and 704 collectively constitute an inter-band tunneling injection region.
  • the electrons in the full valence bands near the interface with the 701 layer in the 702 quantum well layer can be injected through the inter-band tunneling to the interface at the 703 layer near the 704 layer, thereby becoming conduction band electrons. These conduction band electrons are further tunneled through a thin layer of 704 layers.
  • the sub-barrier will be injected into the electron oscillating region composed of 705 layers.
  • the holes left by the valence electron tunneling into the conduction band in the 702 quantum well layer will be injected into the hole oscillation region composed of the 701 layer through in-band tunneling.
  • the electrons and holes obtained in the carrier oscillation region also meet the requirements for the initial characteristics of the carrier by Bloch oscillation.
  • the purpose of introducing 704 is to increase the probability of inter-band resonance tunneling between 702 and 703 layers by forming a thin conduction band barrier.
  • the thickness of this 703 layer is ⁇ iH3 ⁇ 4 .
  • the carrier oscillating regions shown in Figures 3 and 5-7 are all composed of a uniform semiconductor layer.
  • the carrier oscillating region can also be composed of multiple semiconductor layers, and each layer can also be non-uniform (such as achieved by passing through it), as long as the entire structure supporting the inter-band tunneling injection region and the carrier oscillating region is supported. Inter-band tunneling occurs first in the inter-band tunneling injection region.
  • the carrier oscillation region of the structure shown in FIG. 8 is composed of two semiconductor layers, the electron oscillation region is composed of two layers 806 and 807, and the hole oscillation region is composed of two layers 801 and 802. This structure is similar to the structure shown in FIG. 3, and also uses a coupled double quantum well structure to form a tunneling injection region.
  • the two quantum well layers are 803 and 805, and the thin barrier layer between the two wells is 804.
  • the device may also include only one carrier oscillation region.
  • the thickness of the cavity oscillation region can be made smaller than the space expansion of the empty 1 och oscillation, or the thickness of the electron oscillation region can be made smaller than that of the electron B 1 och oscillation.
  • An extreme example of a carrier oscillation region consisting of multiple layers is the use of a short-period superlattice as the carrier oscillation region. Fig.
  • 9 is a band diagram of a device using a superlattice as an electronic oscillation region.
  • the device ’s hole oscillation region 901 is a layer of uniform semiconductor material.
  • 905 is composed of two materials with different band gap widths.
  • the superlattices obtained are alternately arranged with a period of d.
  • the forbidden band width of the semiconductor material with a smaller forbidden band width constituting the superlattice should not be smaller than the forbidden band widths of the materials constituting the quantum well layers 902 and 904.
  • the band edge energy difference and the respective thicknesses of the two semiconductor materials constituting the superlattice in the conduction band are important parameters that determine the band width of the superlattice lattice, as well as important design parameters of the device.
  • the diameter of the micro-Brillouin region is inversely proportional to the period d of the superlattice, which is smaller than the Brillouin region of the bulk material, so it can be obtained under the same electric field. Higher frequency electromagnetic radiation.
  • the quantum oscillator device of the present invention can effectively use the stress to tailor the energy band structure of the semiconductor.
  • the light hole band Under the action of biaxial tensile stress, the light hole band will have higher energy at the top of the valence band; the heavy hole will have higher energy under compressive stress.
  • the selection rule in the center of the Brillouin zone, only the electron energy level of the light hole band and the electron energy level of the conduction band are combined, so that the top of the light hole band has a higher energy tensile stress.
  • the state is more advantageous for achieving inter-band tunneling. For this reason, the potential provided by the growth of lattice mismatched materials can be fully utilized to try to make the entire device structure or the local area that has lost valence electrons in a biaxial tensile stress state, so that inter-band tunneling is easier to achieve.
  • a GaAs / GaAlAs heterostructure can be grown on a Si substrate, so that biaxial tensile stress exists in the entire device structure; and when an InP substrate-based In the InGaAs / InP heterojunction system, in order to make biaxial tensile stress in the quantum well layer, the composition of In in the InGaAs constituting the quantum well layer can be made slightly smaller than the composition when InGaAs and InP lattice match (0. 53).
  • the biaxial tensile stress in the epitaxial layer can be equivalent to the superposition of uniaxial substress and net fluid tension perpendicular to the epitaxial plane (along the growth direction and parallel to the direction of the applied electric field). Therefore, after the device is manufactured, the uniaxial compressive stress in the direction of the electric field can also be applied to make tunneling in the inter-band tunneling structure easier.
  • the valence band tops of the layers shown in Figures 3 and 5-9 should be considered as the energy levels corresponding to the light hole band tops.
  • inter-band tunneling through the injection region can be more easily occurred.
  • Another external condition that can improve the performance of the quantum oscillator device of the present invention is to make the device operate at Lower temperatures, for example, make it work in liquid nitrogen or even liquid helium. At low temperatures, the lattice vibration of semiconductor materials is weakened, and the number of phonons is correspondingly reduced. This is not only beneficial for inter-band tunneling where wave vector conservation occurs in the tunnel injection region, but also weakens electrons or holes in the oscillation region. Non-scattering during B 1 och oscillation.
  • FIG. 10 is a schematic cross-sectional view of an embodiment of a quantum oscillator device according to the present invention.
  • the tunneling injection region and the carrier oscillation region in the device have an energy band arrangement form shown in FIG. 3.
  • the entire device structure was obtained by growing a GaAs / GaAlAs heterojunction system on a (100) Si substrate using molecular beam epitaxy (MBE) technology.
  • MBE molecular beam epitaxy
  • Si substrate growth can cause biaxial tensile stress in the entire structure including the inter-band tunneling injection region. The existence of this tensile stress contributes to the occurrence of inter-band tunneling.
  • the effects of inter-band tunneling have been described previously.
  • a thick buffer layer composed of a III-V compound material is grown, and then the structure required for the device is regrown.
  • a mesa device is made through a photolithography, chemical etching, dielectric film deposition, metal evaporation, stripping, and alloying process similar to that of a photodiode.
  • "U” in the figure indicates that the grown semiconductor material does not intentionally add a dopant during the growth process; "+" in the upper right corner of n and p indicates heavy doping.
  • the tunneling injection region of the semiconductor quantum oscillating device is composed of two undoped 3 ⁇ 4 ⁇ As sandwiched with a layer of Ga A 1 As. Among them, the two doped layers constitute two quantum wells with a thickness of 100 Angstroms. Be two
  • the GaAs well layer sandwiched with an undoped AlGaAs thin barrier layer defines a boundary for each quantum well, with a thickness of 50 angstroms and a composition of A1 of 0.2;
  • the two undoped AlGaAs layers constitute the electron and hole oscillation regions, respectively, and define the other boundary of each quantum well.
  • the composition of the two layers A 1 is 0.40 and the thickness is 2000 angstroms.
  • the n-type GaAlAs and the heavily doped n-type GaAs together form a contact region that is in contact with the electronic oscillation region.
  • the corresponding contact electrode also includes an AuGe / Ni ohmic contact made on the heavily doped n-type GaAs. It constitutes a non-coherent electron collection terminal.
  • the other contact region that is in contact with the hole oscillation region is composed of p-type AlGaAs and heavily doped p-type
  • GaAs are formed together, and the corresponding contact electrodes include AuZn European contacts made on heavily doped p-type GaAs, which constitute a non-coherent hole collecting end.
  • the introduction of heavily doped n-type and p-type GaAs is to improve the characteristics of European contact.
  • the A 1 composition of n-type A 1 GaAs and p-type A 1 GaAs is the same as the A1 composition of the undoped AlGaAs constituting the carrier oscillation region, which is also 0.4, and both have a thickness of 2000 angstroms and a doping concentration of both.
  • the role of these two layers is to prevent incoherent electrons and holes from being injected into the carrier oscillation region from the side close to the electrode. This condition can be satisfied when the strong electric field tunneling through the injection region and the carrier oscillating region is completely generated by the positive and negative space charges confined to the two layers, respectively.
  • the lower limit of the strong electric field required for device operation can be determined by the critical electric field Ec required for inter-band tunneling to occur.
  • the thickness of the quantum well layer in the device of this embodiment is 10 nm
  • the band gap of GaAs is
  • the spatial expansion of the Bloch oscillation can be calculated by:
  • e is the electronic charge
  • F is the electric field strength of the oscillating region
  • ⁇ is the width of the energy band in the direction of the electric field.
  • this width corresponds to the conduction and valence band widths of the carriers in the direction of movement (epitaxial growth direction) under the action of the electric field, respectively.
  • an undoped semiconductor layer constituting the oscillating region is formed. The thickness is larger than the spatial expansion of the Bloch oscillation determined by the above formula.
  • the width of the conduction and valence bands along the ⁇ axis of the Brillouin region is in the range of 2-4eV, and the size is 5 x l0 5 V / cm
  • the electric field of 2 can be obtained according to formula (3), and the corresponding size of L is 400-800 Angstroms. It can be seen that, in this embodiment, the thickness of the two oscillating regions is designed to be 2000 Angstroms to meet the above requirements.
  • FIG. 11 shows the current-voltage characteristic curve measured at room temperature for the device shown in FIG. 10 using a QT-2 type transistor grapher.
  • the two electrodes of the device are connected to the collector and emitter terminals of the instrument, and the base terminal of the instrument is not used.
  • the shape of the obtained characteristic curve is the same as that in FIG. 2, but the peak value of the current density increases to 300 A / cm 2 .
  • the current-voltage characteristics of the device are at a critical voltage with a magnitude of about 20V.
  • the critical voltage can be estimated based on the thickness of the two oscillating regions and the critical electric field required for tunneling between bands.
  • the voltage drop across the entire undoped region (total thickness 4250 ⁇ ) constituting the implanted region and the oscillating region within the device is 24.
  • leV the voltage drop across the entire undoped region (total thickness 4250 ⁇ ) constituting the implanted region and the oscillating region within the device.
  • the threshold voltage and the measured value are in good agreement.
  • the characteristics of the semiconductor quantum oscillator device of the present invention are characterized by a negative
  • Negative resistance segment 3 corresponds to the back-coherent and non-coherent carriers as a system whose state is far from the quasi ⁇ order state of the thermal plane, and the spatial local area of the carrier that makes Bloch oscillatory motion. Space charge effect.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Optics & Photonics (AREA)
  • Nanotechnology (AREA)
  • Chemical & Material Sciences (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biophysics (AREA)
  • Manufacturing & Machinery (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Electromagnetism (AREA)
  • Ceramic Engineering (AREA)
  • Semiconductor Lasers (AREA)
  • Recrystallisation Techniques (AREA)
  • Bipolar Transistors (AREA)

Description

半导体量子振荡器件 技 域
本发明涉及量子效应半导体器件， 尤其涉及半导体量子振荡器件， 该 类器件发射电磁糍射以响应所加的电场， 发射的电磁辐射的频率处于微波 的高端和红外的低端之间的电磁波语范围。
背景技术
与本发明有关的基本理论考虑是晶体中电子在外加均匀稳态电场下的 行为。 60多年以前, F. Bloch (参见 F. Bloch, Z. Phys. 52, 555 (1928) ) 和 C. Zener (C. Zener, Proc. R. Soc. 145, 523 (1934) )的工作就表明， 如果把晶体中的电子看作 Bloch函数组成的波包， 那么在不受散射作用的情 况下， 晶体中某个能带中的电子为了响应外加电场将在被激发到能量更高 的能带以前、 在晶格周期势和所加外电场的共同作用下在波矢空间做周期 运动。 该周期运动的频率为 eFa/h， 其中 e是电子电荷， F为电场强度， a为 晶格常数， h为普朗克常数。 电子在波矢空间（k空间）的周期运动意味着 它在实空间也做周期运动。 电子的这种周期运动一般被称作布洛赫 ( Bloch )振荡（或齐纳 ( Zener )振荡， 还有的称为 Zener-Bloch振荡或 Bloch-Zener振荡）。 Bloch振荡是弹道加速的电子在布里渊区（Br i l louin) 边界受到布 (Bragg)反射从而在布里渊区内 期运动引起的。 以上基 于 Bloch态组成的波包对电场作用下电子运动的描述一般称为半经典描 述。 更进一步的理论工作表明， 对于基于电场作用下准束缚 Wannier- Stark 态组成的波包对电子运动的完全量子力学描述来说， Bloch振荡对应于态间 互相干涉产生的量子节拍（quantum Beats)。 关于 Bloch振荡的理论分析可 参见 G. Bastard和 R. Ferreira所著题为 "在加偏压的半导体超晶格中瓦尼 尔―
Figure imgf000003_0001
一文 ( Spectroscopy of Semiconductor Microstructures, NATO AS I Series (Plenum, New York, 1989) , p. 333 ) 。 为了实现 Bloch振荡， 电子至少在经历一个完整的振荡周期以前不被激发到 能量更高的能带（带间隧穿或 Zenner隧穿）， 同时也不受到散射。 关于带间 隧穿， 在不考虑声子影响的情况下， 基于单电子近似从理论上已严格证明 了其几率的上限。 结果表明电子在隧穿进入高能带以前可以经历多个振荡 周期（参见 A. Nenciu and G. Ninciu, J. Phys. A14, 2817 (1981) )。 因此， 带间隧穿不是实现 Bloch振荡的主要限制。 关于散射， 电子受到的散射包括 声子散射和杂盾散射。 目前， 一般认为由于散射的存在， 对于所有适当的 电场强度， 在通常的固体（包括半导体）中 Bloch振荡是观察不到的（参见 G. von Plessen and P. Tomas, Phys. Rev. 45, 9185 (1992) )。 P. Robl in 和 M. W. Mul ler (J. Phys. C: Sol id state Phys. 16 4547 (1983) )曾对可实 ^Bloch振荡（该文献中称为相干 Zener振荡）的电子的特性进行过研究， 发 现只有准相干（Quas icoherent)的电子才能实现 Bloch振荡， 准相干的电子 表现出许多经典粒子的特性， 可被称为类经典（class ical l ike)或弹道电 子。
L. Esaki和 R. Tsu从应用的角度在美国专利 3626328中提出了一种利用 半导体超晶格结构实 1 och振荡的半导体 ^^荡器件。 其出发点是利用超 晶格的微布里渊区（minizone)较正常晶格的布里渊区小从而使得电子在电 场的作用下更容易避开散射的限制来实现周期运动。 该申请的目的是利用 超晶格中电子的 Bloch振荡获得一种可发射高频电磁辐射的器件。 到目前为 止， 该项专利所提出的器件实际上一直没有被制造出来 (参 JU. Esaki, in Science and Technology of Mesoscopic Structures, Springer-Verlag, 1992, P. 3)。 关于利用半导体体材料实现 Bloch振荡从而发射高频电磁辐 射的器件， M. W. Mul ler, P. Robl in和 D. 1. Rode (见 Workshop on Submicron Devices Phys ics, ed. H. L Grubin, (New York: Plenum, 1983) , p. 261)也曾提出过一种器件设想 (称为 Zener振荡器)， 希望利用导带电子隧 穿过异质结势垒实现载流子注入。 P. Robl in, M. W. Mul ler (Semicond. Sci. Techno 1. 1 (1986) 218 )曾指出， 为实 于 Bloch振荡的器件， 注 入电子的相位必须是一致的。 他们还就化合物半导体中声子对做 Bloch振荡 运动的电子的散射进行了分析， 指出只要 Bloch振荡的频率大于纵光学声子 的最大频率， 声子的影响就可以被避开。 此外， 他们还更尽一步指出在体 半导体中实 »loch振荡的主要困难是如何使其开启。 尽管所有这些观点都 有其合理性， 但他们得出的结 f p是在电子注入阶段高的极性声子散射率 ^^法避开的， 也就是说， 上述设想的器件同样没有得到所希望的结果。 究其原因是器件中所拟采用的 "与时间有关的隧穿（time-dependent tunnel ing) " 这一电子注入机理实际上无法实现， 同时， 这一注入^ US也 无法避开高的极性声子散射。 因此， 如何能找到一种新的电子注入机理， 使得在注入阶段电子能避开极性声子散射的影响， 注入后电子的相位又能 保持一致， 是获得能实际工作的基于 Bloch振荡的量子振荡器件的关键。 另 外， 目前所有关于利用半导 Ν"料实 ¾loch振荡的器件设 注意力集 中到了导带中的电子， 对于利用半导体中的另一种载流子 -价带中的空穴 的运动来实 1 och振荡还没有见到报
发明内容
本发明的目的在于提供基于载流子（包括导带电子和价带空穴)全新注 A^^L理实现 loch振荡的半导体量子振荡器件。 本发明人所提出的注 不仅可以克服现有技术中无法避开的在注入阶段存在的高的极性声子散 射， 同时也能使注入电子间的相位以及注入空穴间的相位保持一致。
为了 上述目的， 本发明人对实¾Bloch振荡的条件进行了广泛而深 入的研究， 首先发现了如下事实：
1) . 半导体中声子对满价带中电子的散射作用远小于对通常掺杂半 导体中价带中电子或导带中电子的散射。 因为对于半导体的被电子填满的 价带， 如果其内部电子受声子散射， 则由于带内没有空的态电子只有可能 被散射到导带。 而实际上由于导带和价带之间存在远大于平均热运动能量 的禁带， 这一散射的几率是^ L小的。
2) . 在强电场作用下， 对于不掺杂的高纯半导体， 其被填满的价带中 最顶部（波矢为零)的电子可以通过能带间的隧穿被激发到导带， 从而可以 在导带和价带顶分别引入能自由运动的电子和空穴。 根据 1)的结果， 满价 带中价带顶的电子在隧穿发生之前受声子散射的影响很弱， 因此， 如果设 法使声子不参与带间隧穿， 那么所获得的自由导带电子和价带空穴就可以 避开声子散射的影响。 此外， 由于通过隧穿被激发到导带的电子只是位于 价带顶的电子， 而它们的波矢都接近零、 无声子参与的隧穿过程中波矢又 保持守恒， 因此， 如果再设法使带间隧穿只是在局部位置上发生的话， 那 么得到的导带电子和价带空穴的相位也将是一致的。
3) . 根据 P. Robin和 M. Mul ler的分析， 通过 4吏振荡频率大于最大的 纵光学（L0)声子频率来避开声子对做 Moch振荡运动的电子的散射所要求 的电场强度应大于 1000kVcm-l， 这一要求和半导体中发生带间隧穿对电场 强度的要求是吻合的。
4) . 对于采用分子束外延 (MBE)和金属有机物化学气相淀积 (M0CVD) 等原子层精度生长手段生长的半导体异质结多层结构， 通过对各层的厚 度、 组分和 /或应力的控制可以 4吏得强电场作用下的带间隧穿只在整个多层 结构的局部发生， 并且不需要声子的参与。 结构中发生带间隧穿的部分可 以被用作 B 1 och振荡器件的注入区， 以注 > a位一致的相干电子和空穴。
根据以上发现， 本发明提供了能实际工作的基于 Bloch振荡的量子振荡 器件， 其主要工作原理是利用不掺杂半导体多层结构中局部发生的半导体 满价带顶部的电子到空的导带的无声子参与的带间隧穿（也称为 Zenner隧 穿）实现相位一致的相干电子和空穴的注入。
本发明的半导体量子振荡器件， 包括一个由多个半导体层构成的异质 结构和给上述半导体异质结构施加电压的装置， 其特征在于：
所述半导体异质结构包括隧穿注入区和与其直接相接并位于其两側 的两个载流子振荡区-电子振荡区和空穴振荡区， 所述施加电压的装置将 电压加在两个振荡区上， 引起隧穿注入穿区局部的价带电子通过带间隧穿 it^到导带， 在两个振荡区内分别引入做量子振荡运动的电子和空穴， 产 生远红外辐射。
所述的半导体量子振荡器件还包括位于所述两个栽流子振荡区不和 隧穿注入区相接一側的两个接触区和相应的接触电极， 所述施加电压的装 置通过两个接触电极把电压加在两个载流子振荡区上。
所述半导体量子振荡器件中所述隧穿注入区和载流子振荡区由禁带 宽度不同的多个半导体外延层按特定顺序排列而得到的异质结构构成。
目前， 利用现有的两端和三端半导体器件构成的振荡器 获得频率 大于 300GHz的电磁辐射。 另一方面， 在比中红外 (5-8μηι)更长的波段上也没 有象近红外半导体激光器那样的能将直流电能高效地转换为光能且工作速 度高的固态光源。 总之， 对于亳米波的高端和远红外的低端之间的电磁频 区域， 目前还缺少体积小、 效率高、 速度快的电磁犒射源， 而半导体中 载流子 Β 1 och振荡所产生的电磁辐射正好覆盖电磁频 的这一区域。 因此， 本发明所提供的基于 B loch振荡的半导体量子振荡器件将会为充分利用这 一区域的电磁波资源铺平道路。
本发明的附图说明：
图 1是本发明的利用无声子参与带间隧穿实现栽流子注入的半导体量 子振荡器件的结构示意图。
图 2是图 1所示器件的电流电压特性曲线的示意图， 它说明对应于带间 隧穿开始发生存在一临界电压 Vc。
图 3是可用于图 1所示器件的一种带间隧穿注入区和载流子振荡区结构 的解释性能带图。
图 4是图 3所示隧穿注入区和载流子振荡区在外加电压为临界电压时的 能带示意图。
图 5 - 7是可用于图 1所示器件的其它带间隧穿注入区和载流子振荡区 结构的解释性能带图。
图 8 是对图 3所示带间隧穿注入区和栽流子振荡区结构进行稍许改变 后得到的结构的解释性能带图。
图 9是一种采用超晶格结构作为电子振荡区的器件的能带图.
图 10是本发明的半导体量子振荡器件的一个实施例的剖面示意图。 图 11是对图 10所示实施例实测得到的电流电压特性曲线。
下面参照附图对本发明作进一步的描述。
图 1是本发明的包括带间隧穿注入区和载流子振荡区的半导体量子振 荡器件的结构示意图。 图中的数字 ΙΟΟ 整个器件， 具体包括带间隧穿注 入区 102、电子振荡区 104和空穴振荡区 106、与电子振荡区相接的接触区 108 和相应的金属接触电极 112, 以及与空穴振荡区 106相接的接触区 110和相应 的金属接触电极 114。该器件工作时，给上述半导体结构施加电压的装置（未 作图示）通过 112和 114两个接触电极向该半导体结构施加一定的电压， 电 极 112所加电压的极性为正。 该电压在带间隧穿注入区 102与两个载流子振 荡区 104和 106组成的结构内产生强电场。 该电场在隧穿注入区内首先诱发 价带到导带的不需声子参与的带间隧穿， 从而产生相位一致的相干电子和 空穴并分别将其注入到电子振荡区 104和空穴振荡区 106。 注入到振荡区的 电子和空穴在强电场和半导体的周期晶格势的共同作用下做量子振荡运 动， 产生超高频辐射。 辐射的出射方向与所加电场的方向垂直， 偏振方向 和电场方向平行。 因此， 本发明的半导体量子振荡器件很象側面发光的半 二 fel管，
Figure imgf000008_0001
对于本发明的半导体量 子振荡器件， 通过象半导体激光器一样利用解理面构成共振腔， 或采用其 它的手段使所发射的电磁辐射反馈回器件内， 就可以构成^ ^器。
载流子在振荡区做 Bloch振荡的频率可由下式确定 hK 其中 e为电子电荷， F为电场强度， h为普朗克常数， κ为布里渊区沿电场方 向的直径， λ为与具体能带结构有关的因子。 对于 GaAs等化^ ^半导体， 其 导带除了在布里渊区中心有一极小值外， 在 Δ和 Λ等高对称性的轴上还有一 个次极小值。 根据半经典描述， 这 (吏得当电场沿这些方向时， Bloch振荡 的频率不等于简单理论给出的频率 (ν=2 π eF/hK) , λ这个因子就^ ^于此而 引入的。 虽然目前对于能带结构的细节如何影响振荡频率尚不完全清楚， 但估计其值应该在 1 - 2之间。 对于价带的空穴能带， 由于不存在次极值， λ的值应取为 1。 对于 GaAs, 当电场为 5 χ 105V/cm2时， 利用上式可计算出 hv=27 meV。 可见这时 Bloch振荡所发射的电磁辐射将在电磁波语的远红外 区。
图 1中的接触电极 112和 114是本发明的量子振荡器件和外部世界的接 口， 其作用包括两个方面， 一是通过它们可以施加外电压从而在带间隧穿 注入区和栽流子振荡区产生器件工作所需的强电场， 另外就是接收在振荡 区做 Bloch振荡运动的载流子中那些由于受到散射相位不再保持相干的载 流子。 这些载流子被接触区和相应的电极收集就形成了器件端口的电流。 应该特别指出的是， 本发明的量子振荡器件对接触电极的要求是电子振荡 区一側的电极不能向电子振荡区注入非相干的电子， 而空穴振荡区一側的 接触电极不能向空穴振荡区注入非相干的空穴。 如果这一要求得不到满 足， 在达到带间隧穿所需的强电场以前， 这些非相干载流子在电场的作用 下就会诱发雪崩击穿， 使得无法通过带间隧穿得到相位一致的相干载流 子。 因为金属电极通过隧穿将可以向载流子振荡区注入非相干的载流子， 故金属电极和不掺杂的载流子振荡区直接接触不容易满足上述要求。 原则 上说， 可在金属电极和载流子振荡区之间加入一层介盾层， 但实际上是不 行的。 因为这时虽然接触电极不会向栽流子振荡区注入非相干的栽流子， ^^介质和载流子振荡区的界面将会存在界面态。 在电场的作用下这些界 面态将作为载流子的产生中心， 从而也会向载流子振荡区注入非相干的栽 流子。 另外， 即使在金属电极和载流子振荡区之间加入一 ^质层的方案 可行， 该半导体量子振荡器件也只能在外加脉冲条件下工作。 防止接触电 之间加入掺杂的半导体接触区， 即图 1中的 108和 110， 并使得接触电极和接 触区之间的接触为欧姆接触。 两个接触区的掺杂类型应该是不同的， 和电 子振荡区相接的接触区 112的掺杂类型应该为 n型， 而和空穴区相接的接触 区 114的导电类型应为 p型。 总之， 本发明的半导体量子振荡器件与一个反 向偏置的 P-I- N二极管很类似， 其独特之处在于其 I区是由带间隧穿注入区 和栽流子振荡区共同构成的复杂结构。 应该特别指出的是， 若两个接触区 由具有相同的导电类型的半导体层构成 (二极管结构为 N-I-N或 P-I- P) , 则 不能防止接触电极向载流子振荡区注入非相干的载流子。
图 2给出了本发明的半导体量子振荡器件所应具有的直流电流-电压 特性的示意图。 该直流电流-电压特性曲线有一拐点， 该拐点对应的电压 就是带间隧穿开始发生时所对应的外加电压， 可称为临界电压。 当外加电 压小于临界电压时， 器件的电 u为零， i ^t应于直流特性曲线的 20H 当 外加电压大于临界电压时， 通过带间隧穿注入到栽流子振荡区的相干电子 和空穴 «loch振荡运动， 器件发射电磁辐射。 与此同时， 振荡过程中因受 到散射而相位不再相干的电子和空穴被接触电极收集所形成的电流构成直 曲线的 202段。 应该指出的是， 由于器件中的相干和非相干载流子作 为一个整体其状态远离热平衡态， 这将使得器件的电流电压特性与测量方 法及条件有关。 在图 2中将特性曲线的 202段画成虚线就是为了反映这一 点。 另外， 由于做 Bloch振荡运动的相干电子和空穴在空间上是局域化的， 因此会产生空间电荷效应。 该空间电荷效应对带间隧穿的反馈作用将使得 器件的实际电流电压特性比图 2给出的特性要复杂， 并与器件的具体结构参 数有关。 尽管如此， 存在一和带间隧穿开始发生相对应的临界电压这一特 点应该是共有的。 本发明的量子振荡器件正常工作时的外加电压应大于该 临界电压。 在下面的典型实施例中将可以看到对样品器件进行实测得到的 电流电压特性。
本发明所提供的半导体量子振荡器件的核心部分为带间隧穿注入区
(即图 1中的 102 )和载流子振荡区（即图 1中的 104和 106 )。 将本发明的器 件的核心部分划为带间隧穿注入区和载流子振荡区只是为了叙述的方便， 这两个区由于是直接相接的， 因此只有合在一起才能实现各自的功能。 下 面以能带图的形式说明在如图 1所示的本发明的量子振荡器件中这两个区 是如何实现的。 这两个区可由多个不掺杂半导体层通过适当的組合而形 成。 通过不摻杂不仅可以在这两个区内形成带间隧穿和 Bloch振荡所需的强 电场， 同时也能使御 loch振荡运动的载流子受到的散射减弱。 图中给出的 各层的带隙都为该层材料的布里渊区中心 Γ点的直接带隙。
图 3是一种可用于本发明的量子振荡器件的带间隧穿注入区和载流 子振荡区结构的能带图。 如图所示， 301为一禁带宽度较大的半导体层， 例 如 GaAlAs, 作为空穴 (或电子）电子振荡区； 305也为一禁带宽度较大的半导 体层， 例如 GaAlAs, 作为电子 (或空穴)振荡区。 对于 301和 305这两层的半 导体材料的最小带隙是否为直接带隙无特别要求。 当为直接带隙时， 例如 GaAlAs中的 A1组分小于 0. 45， 图中所画出的能带图就是通常的能带图， 导 带边对应布里渊区中心电子的能量； 当为间接带隙时， 例如 GaAlAs中的 A1 组分大于 0. 45, 图中的导带边仍对应布里渊区中心电子的能量， 尽管这时 该点对应的导带边的能量已不是导带的最低能量。 图中， 302和 304为两个 禁带宽度较小的半导体层， 例如 GaAs, 303为一禁带宽度较大的半导体层， 例如 AlGaAs。 以 301和 303两层作为限制层， 层 302对电子和空穴同时构成一 量子势阱-量子阱； 以 305和 303两层作为限制层， 层 304对电子和空穴构成 另一量子阱。 和普通势阱， 例如双异质结构中存在的势阱不同， 量子阱是 指至少存在一个量子化能级的势阱。 为此要求阱的宽度要 ：小， 即阱层的 厚度要很薄； 同时要求阱的深度， 即限制层和阱层的带边能量的差要较大。 对两个阱层之间的势垒层 303的最小带隙是否为直接带隙也无特别要求， 但 该层应当允许两个阱层的量子化能级之间发生耦合， 即形成耦合双量子阱 结构， 从而该层的厚度也 艮薄。 （有关量子阱方面知识可参见， (1) The Special issue of "Semiconductor Quantum Wel ls and Superlatt ices: Phys ics and Appl ications " of the IEEE Journal of Quantum Electronics, Vol. QE-22, Sept. , 1986; (2) E. E. Mendez and K. von Kl itzing (1987) , "Phys ics and Appl ications of Quantum Wel ls and Superlattices ", NTAO ASI Series; Series B, Phys ics: 170, Plenum, New York; (3) C. Weinbuch, B. Vinter, Quantum Semiconductor Structures, Academic, Press, 1991)。
302、 303和 304三层是带间隧穿发生的区域。 在外加电压产生的强电 场的作用下， 当量子阱层 302最左側的价带顶的 和量子阱层 304最右側 的导带底的^ «本对齐时， 层 302中的价带电子能级将和层 304中的导带 电子^ ¾1产生耦合， 这种鵜合将会使层 302中满价带最顶部的电子在无声子 参与的情况下共振隧穿到层 304的导带。 和两个阱层直接相接的两个势垒层 的禁带宽度比阱层的大， 它们内部在使两个阱层发生带间隧穿的电场下不 会发生带间隧穿， 因而， 整个结构中带间隧穿只是在隧穿区内发生。 通过 带间隧穿进入 304层导带的电子在强电场的作用下将会通过导带带内隧穿 电子振荡区 305。 由于进入电子振荡区的电子来自价带顶， 即波矢都等 于零， 在实空间这些电子又都来自同一个很薄的量子阱层， 所以如此产生 的导带电子是准经典的电子， 满足了的 Bloch振荡对注入电子的初始特性的 要求。 价电子发生带间隧穿的同时在层 302留下的空穴是准经典的空穴， 该 空穴也^ 过价带带内隧穿 ¾ 到空穴振荡区 301 , 同样满足了空^ B 1 och 振荡对注入空穴初始特性的要求。 图 4是图 3所示隧穿注入区和载流子振荡 区在外加电压为临界电压时的能带示意图， 说明了发生带间隧穿时的情 况。 根据该图可以定义一个临界电场 Ec。 半导体量子振荡器件工作时， 外加 电压在隧穿注入区和栽流子振荡区产生的电场应大于该临界电场以使得带 间隧穿能够发生。 该临界电场对应的外加电压就是图 2中的临界电压。 该电 场的大小可通过下式计算：
Fc = ~~ ¾ ( 2 ) 其中， Eg为两个量子阱层的禁带宽度， dwl和 d，2分别为两个量子阱层的厚度， db为两个量子阱之间薄势垒层的厚度。
利用外延生长技术， 除了以 GaAs或 Si为基底采用 GaAs/GaAlAs或 GalnP/GaAs异质结系统可获得图 3所示的能带带边分布的结构外， 还可用 InP 为基底采用 InGaAs nP、 InGaAs/Al InAs或 InGaAsP/InP异质结系统， 或者以 GaSb、 AlSb或 ZnTe为基底采用 GaSb/GaAlSb异质结系统。 目前， 采用 分子束外延 (MBE)和金属有机物化学汽相淀积 (M0CVD)等外延生长技术生长 以上异质结系统已广为人知， 具体细节可参见： L. L. Chang and K. Ploog, eds, "Molecular Beam Epi taxy and Heteros tructures, ", Proc. Er ice 1983 Summer School. Mart inus Ni jhoff, The Hague, 1985 和 J。 Crys Growth上的有关文章。
图 5是该器件另一种隧穿注入区和载流子振荡区结构的能带示意图。 该 结构和图 3所示的结构 a似， 只是用一个宽度较大的量子势阱替换图 3中 的耦合双量子阱。 当将图 3中两个阱层中间的薄势垒层 303换成和两个阱层 一样的禁带宽度较小的直接带隙材料时， 302、 303和 304三层就构成一宽度 较大的量子阱， 由此就可得到图 5所示的结构。 在外加电压产生的强电场的 作用下（为了和图 1对应， 假设电场的方向从构成电子振荡区的层 503指向构 成空穴振荡区的层 501)， 当量子阱层 502最左側的价带顶的能级和该层最右 侧的导带底的能级基本对齐时， 该层中最左侧的价带电子能级将和最右侧 的导带电子能 互耦合， 这种耗合将^ 内最左側满价带最顶部的电 子在无声子参与的情况下共振隧穿到同一层最右側的导带。 由于在波矢空 间（k空间）发生隧穿的电子来自价带顶， 即波矢都等于零， 在实空间这些 电子又都来自同一个量子阱层的最左側， 所以如此产生的导带电子也是准 经典的电子。 这些电子通过导带带内隧穿进入电子振荡区满足了 Bloch振荡 对注入电子的初始特性的要求。 价电子发生带间隧穿的同时在阱层 502的最 左侧留下准经典的空穴， 这些空穴通过价带带内隧穿进入空穴振荡区也满 足了空 ^Bloch振荡对注入空穴初始特性的要求。 具有该种能带带边分布的 结构 同 样可以利 用 GaAs/GaAlAs 、 GalnP/GaAs 、 InGaAs/InP 、 InGaAs/Al InAs. InGaAsP/InP 和 GaSb/GaAlSb等异质结系统来实现。 图 6是本发明半导体量子振荡器件的又一种隧穿注入区和载流子振荡 区结构的能带图。 该器件的带间隧穿注入区和载流子振荡区由三个半导体 层 601层、 603层和 602层构成， 它们构成 Π型排列的异貭结。 关于半导体异 质结的能带排列类型可参见 S. M. Sze ed. "High Speed Semiconductors", John Wi ley &Sons, 1990， P. 20 1992。 关于 602层， 对其最小的带隙是否 为直接带隙无特别要求， 但要求其厚度很小以便对空穴构成一量子势阱。 为了和图 1对应， 假设外加电场的方向由 603层指向 601层。 这时， 603层构 成电子振荡区， 在外加强电场的作用下， 当阱层 602最左侧的价带顶的能级 和 603层电子振荡区最左側的导带底^^对齐时， 阱中的价带电子可以通过 带间隧穿注入到电子振荡区， 价电子隧穿进入导带在阱内留下的空穴将在 电场的作用下通过价带内的带间隧穿注入到 601层构成的空穴振荡区。 由此 得到的电子和空穴也同样满 ζ 1 och振荡对载流子初始特性的要求。 该结构 可利用在 InP衬底上生长的 AlInAs/InP异质结系统来实现， 该异质结系统的 能带排列为 Π型。 Al InAs的价带顶有更高的能量， 可用于形成阱层 602， 相 应地， InP可用作电子和空穴振荡区。 Π - VI族化合物半导体 ZnTe和 CdSe构 成的异质结系统的能带排列也为 Π型， ZnTe的价带顶的能量较高， 可用于 构成量子阱层 602， CdSe可用于构成栽流子振荡区。
图 7是本发明的半导体量子振荡器件又一种带间隧穿注入区和载流子 振荡区结构的能带图。 该半导体量子振荡器件的带间隧穿注入区和载流子 振荡区由三种不同半导^ 料共五层构成， 其中 701、 703和 705三层为同一 种半导体 料， 例如 InP; 702为另一种材料， 例如 InGaAs, 该层和 701和 703 层构成的异质结的能带排列为 I型， 并在这两层的限制下构成一量子阱， 因此， 该层的厚度 艮薄； 704层为第三种半导材料， 例如 Al InAs, 该层和 703和 705两层构成的异质结的能带排列为 Π型， 并在这两层的限制下对空 穴构成一量子阱， 因此该层的厚度也要很薄。 该空穴量子阱的深度应小于 由 702层构成的空穴量子阱的深度。 假设电场方向由层 705指向层 701, 这 时 705层构成电子振荡区， 701层构成空穴振荡区； 702、 703和 704三层共同 构成带间隧穿注入区。 在强电场的作用下， 702量子阱层中靠近和 701层界 面处的满价带中的电子可以通过带间隧穿注入到 703层靠近 704层的界面 处， 从而变成导带电子。 这些导带电子通过进一步隧穿过 704层构成的薄电 子势垒后将会注入到由 705层构成的电子振荡区。 702量子阱层中价电子隧 穿到导带留下的空穴通过带内隧穿将会注入到由 701层构成的空穴振荡 区。 如此在载流子振荡区得到的电子和空穴同样也满足 Bloch振荡对栽流子 初始特性的要求。 该能带带边分布所对应的结构中， 引入 704的目的是通过 形成一薄的导带势垒来提高 702层到 703层带间共振隧穿发生的几率， 为此 703层的厚度^ iH¾。
图 3和图 5 - 7个中给出的载流子振荡区均由一均匀半导体层构成。 载 流子振荡区也可以由多个半导体层构成， 每个层也可以是不均匀的 （如通 it 分渐变达到）， 只要构成带间隧穿注入区和载流子振荡区的整个结构支 持带间隧穿在带间隧穿注入区首先发生。 图 8所示的结构的载流子振荡区就 是由两个半导体层构成的， 电子振荡区由 806和 807两层构成， 空穴振荡区 由 801和 802两层构成。 该结构和图 3所示结构 ^似， 也是利用耦合双量子 阱结构构成隧穿注入区。 两个量子阱层分别为 803和 805， 两个阱之间的薄 势垒层为 804。 对于该结构来说， 通过调整 802和 806两个层的厚度和带隙， 可以较图 3所示的结构更好地利用电子的共振隧穿特性。 另外， 针对一个具 体的器件来说， 也可以使器件只包含一个载流子振荡区。 为此， 可以使空 穴振荡区的厚度小于空 1 och振荡的空间扩展， 或使电子振荡区的厚度小 于电子 B 1 och振荡的空间扩展。 栽流子振荡区由多层构成的一个极端的例子 就是利用短周期超晶格作为载流子振荡区。 图 9是一采用超晶格作为电子振 荡区的器件的能带图。 该器件的空穴振荡区 901为一层均匀的半导体材料， 902、 903和 904三层半导体材料构成耜合双量子阱带间隧穿注入区， 905则 为由两种禁带宽度不同的材料交替排列得到的超晶格， 周期为 d。 为了保证 带间隧穿在注入区首先发生， 构成超晶格的禁带宽度较小的半导体材料的 禁带宽度不应小于构成量子阱层 902和 904的材料的禁带宽度。 构成超晶格 的两种半导体材料在导带的带边能量差和各自的厚度是决定超晶格子能带 宽度的重要参数， 也是器件的重要设计参数。 采用超晶格结构作为载流子 振荡区时， 由于其微布里渊区的直径反比于超晶格的周期 d， 较体材料的布 里渊区要小， 因此在相同的电场下可得到频率更高的电磁 射。
为了使隧穿注入区的带间隧穿更容易实现， 本发明的量子振荡器件的 可以有效地利用应力对半导体的能带结构的剪裁作用。 图 3 - 9所给出的能 带图对于价带顶的轻空穴（J = 3/2， mz=l/2)和重空穴 (J=3/2， mz=3/2)没 有进行区分。 这对于构成带间隧穿注入区和栽流子振荡区的半导体层内不 存在应力的情况是合适的。 这时图中的价带顶能级对于轻空穴带和重空穴 带是简并的。 在应力的作用下， 价带顶轻、 重空穴的简并将被解除。 在双 轴张应力的作用下， 轻空穴带在价带顶将具有更高的能量； 压应力时重空 穴带有更高的能量。 由于根据选择定则， 在布里渊区的中心只有轻空穴带 的电子能级和导带的电子能级有耜合， 因此， 使轻空穴带的带顶具有更高 能量的张应力状态对于实现带间隧穿更为有利。 为此， 可充分利用晶格不 匹配材料生长所提供的潜力设法使得整个器件结构或失去价电子的局部区 域处于双轴张应力状态， 以使得带间隧穿更容易实现。 例如， 对于具有图 3 所示能带分布的器件， 可通过在 Si衬底上生长 GaAs/GaAlAs异质结构， 使得 在整个器件结构内都存在双轴张应力； 而当采用基于 InP衬底的 InGaAs/InP 异质结系统时， 为了使得在量子阱层内存在双轴张应力， 可使构成量子阱 层的 InGaAs中 In的組分稍小于 InGaAs和 InP晶格匹配时的组分（0. 53 )。 外 延层内的双轴张应力可以等效为垂直于外延层面（沿生长方向， 和外加电场 方向平行)的单轴亚应力和流体净张力的叠加。 因此， 在器件制作完成后， 也可以通过外加沿电场方向的单轴压应力使得带间隧穿结构内的隧穿更容 易发生。 对于存在应变的情况， 图 3和图 5 - 9所示结构各层的价带顶^^应 被认为是与轻空穴带带顶对应的能级。
除了利用外加的沿电场方向的单轴应力可以使隧穿注入区的带间隧穿 更容易发生外， 提高本发明的量子振荡器件的性能的另一个可以改变的外 部条件是使器件工作在较低的温度下， 例如使其在液氮甚至在液氦温度下 工作。 在低温条件下， 半导体材料的晶格振动减弱， 声子的数量相应地减 少， 这不仅对于在隧穿注入区发生波矢守恒的带间隧穿有利， 还可以减弱 电子或空穴在振荡区作 B 1 och振荡过程中受到的非 散射。
图 10给出了本发明的量子振荡器件的一个实施例的剖面示意图， 该器 件中隧穿注入区和栽流子振荡区具有图 3所示的能带排列形式。 整个器件结 构由在（100) Si衬底上采用分子束外延 (MBE)技术生长 GaAs/GaAlAs异质结 系统而得到。 采用 S i衬底生长可使在包括带间隧穿注入区在内的整个结构 中存在双轴张应力。 该张应力的存在有助于带间隧穿的发生。 关于应力对 带间隧穿的影响前面已有说明。 首先生长一层厚的由 III - V族化合物材料 构成的緩冲层， 然后再生长器件所需的结构。 各层半导体材料生长完成后， 通过光刻、 化学腐蚀、 介质膜淀积、 金属蒸发、 剥离和合金等一^ 类似 于光电二 管的制作工艺制成台面器件。 图中 "U "表示所生长的半导体材 料在生长过程中不有意加入掺杂剂； n和 p右上角的 " + " 表示重掺杂。 该 半导体量子振荡器件的隧穿注入区是不掺杂的两¾^ As夹着一层 Ga A 1 As构 成的。 其中， 不掺杂的两^&人3层构成两个量子阱， 厚度为 100埃。 被两个
GaAs阱层夹在中间的不掺杂 AlGaAs薄势垒层限定了每个量子阱的一个边 界， 其厚度为 50埃， A1的組分为 0. 2; 在此隧穿注入区两侧的另外两个不掺 杂的 AlGaAs层分别构成电子和空穴振荡区， 同时限定了每个量子阱的另一 个边界， 这两层 A 1的组分都为 0. 40， 厚度都为 2000埃。 图中 n型 GaAlAs和重 掺杂的 n型 GaAs—起构成与电子振荡区相接的一个接触区， 相应的接触电极 还包括在重掺杂的 n型 GaAs上制作的 AuGe/Ni欧姆接触， 它构成非相干电子 收集端。 和空穴振荡区相接的另一个接触区由 p型 AlGaAs和重掺杂的 p型
GaAs共同构成， 相应的接触电极包括制作在重掺杂 p型 GaAs上的 AuZn欧 触， 它构成非相干空穴收集端。 重掺杂的 n型和 p型 GaAs的引入是为了改善 欧姻接触的特性。 n型 A 1 GaAs和 p型 A 1 GaAs的 A 1组分和构成载流子振荡区的 不掺杂 AlGaAs的 A1组分相同， 也为 0. 4, 厚度都为 2000埃， 掺杂浓度都为 5
X 1017cnf3。 这两层的作用是防止非相干电子和空穴从靠近电极一侧注入到 载流子振荡区。 当隧穿注入区和载流子振荡区的强电场完全由分别局限于 这两层内的正、 负空间电荷的产生时， 这一条件就能被满足。 器件工作所 需的强电场的下限可由带间隧穿发生所需的临界电场 Ec确定。 将本实施例 器件中量子阱层的厚度 10nm和薄势垒层的厚度 db=5nm以及 GaAs的禁带宽度
Eg=l. 42eV代入式（ 2 ) 可得 Fe = 5. 68 X 105v/cm。 产生该强电场所需单位面 积电荷的数量为 Fcss。/q=3. 6 x l012/cm2。 据此， 对于本实施例器件中掺杂浓 度为 5 X 107cm3的具体情况 ^艮容易得到空间电荷层的厚度约为 700埃。 可 见， 将两个 AlGaAs接触层的厚度设计成 2000埃足以满足使空间电荷区完全 局 接触区这一要求。
Bloch振荡的空间扩展可由下式计算：
Figure imgf000016_0001
其中 e为电子电荷， F为振荡区的电场强度， ΔΕ为能带沿电场方向的宽度。 对于电子振荡区和空穴振荡区， 这一宽度分别对应于载流子受电场作用下 运动方向（外延生长方向)上的导带和价带宽度。 为了使得电子和空穴在做 Β 1 och振荡运动的过程中不受与振荡区相接的掺杂接触区中杂质散射的影 响， 从而影响相位的一致性， 构成振荡区的不掺杂半导体层的厚度要大于 由上式确定的 Bloch振荡的空间扩展。 对于 GaAs等常用的半导体材料， 导带 和价带沿布里渊区 Δ轴方向（实空间 <100>方向上）的宽度在 2 - 4eV这一范 围， 对于大小为 5 x l05V/cm2的电场， 根据（ 3 )式可得到 L的相应大小为 400 - 800埃。 可见， 在本实施例中将两个振荡区的厚度都设计成 2000埃是满足 以上要求的。
图 11给出了对图 10所示器件用 QT - 2型晶体管图示仪在室温下测量得 到的电流电压特性曲线。 测量时器件的两个电极分别与仪器的集电极和发 射极接线端连接， 仪器的基极接线端不用。 在液氮温度下测量时， 得到的 特性曲线的形状与图 2中的相同， 但电流密度的峰值增加， 可达 300A/cm2。 从图中可见， 和图 2给出的解释性电流电压特性一样， 器件的电流电压特性 在一个临界电压， 大小为约 20V。 根据两个振荡区的厚度和带间隧穿所 要求的临界电场可对临界电压作一估计。 对于大小为 Fc=5. 68 X 105V/cm的临 界电场， 器件内构成注入区和振荡区的整个不掺杂区域（总厚度为 4250^) 的电压降为 24. leV„ 考虑到该电压降的一小部分是由两个接触区间大小约 为 GaAs禁带宽度 (1. 42eV)的接触电势差产生的，可得到所需的外加电压（即 临界电压）为 22. 7eV。 可见计算得到的阈值电压和测量值符合得很好。 和 图 2所示器件的解释性电流电压特 ^fe比， 本发明的半导体量子振荡器件特 性的特点是有一负 |¾3和很强的电流为零的回 4， 这一特点可从图 11 直接看出。 另外， 测量中还发现了该器件电流电压特性的另一个特点， 即 特性曲线的形状受所加扫描电压峰值的影响。 随着扫描电压峰值的增加， 图中电流的峰值 jp增加， 回线段 4的宽度也增加。 这两个特点恰好反映了本 发明的半导体量子振荡器件的工作原理不同于所有现有半导体器件的工作 原理， 同时也说明了在器件内部确实发生了带间隧穿载流子注入和 B 1 och振 荡。 如前所述， 作 Bloch振荡运动的电子和空穴并不对器件的端口直流电流 作出贡献。 因此， 图 11中特性曲线的正阻段 3和负阻段 4的电流都应当由振 荡过程中因受到散射相位不再保持相干的电子和空穴被电极收集所产生。 尽管作 B 1 och振荡运动的电子和空穴并不对器件的直流电流作出贡献， 但它 们却会通过空间电荷效应对电流电压特性曲线产生重要影响。 负阻段 3和回 相干和非相干载流子作为一个系统其状态处于远离热平 ί"态的准^ "序状 态以及作布洛赫振荡运动的载流子的空间局域区所对应的空间电荷效应有 关。
上述根据多个半导体层的能带排列及实施例对本发明的半" ^量子振 荡器件的描述着重说明了如何能通过多个具有确定能带结构的半导体层的 特定排列来实现带间隧穿。 应该指出的是， 以上根据能带图所给出的结构 和相应可采用的异质结系统只对本发明的器件起说明作用， 但本发明并不 局限于以上的描述。 基于本发明的精神， 本专业领域的一般技术人员应该 清楚， 对带间隧穿注入区和载流子振荡区当然还可以采用具有其它能带分 布形式的结构和 /或利用另外的异质结系统。

Claims

权 利 要 求
1. 一种半导体量子振荡器件， 包括一个由多层半导体材料构成的结构和 给上述半导体结构施加电压的装置， 其特征在于：
所述由多层半导体材料构成的结构包括隧穿注入区和与其直接相接 并位于其两侧的两个载流子振荡区 -电子振荡区和空穴振荡区， 所述施加 电压的装置将电压加在两个振荡区上， 引起隧穿区局部的价带电子通过带 间隧穿进入到导带， 在两个振荡区内分别引入做量子振荡运动的电子和空 穴， 产生远红外辐射。
2. 根据权利要求 1所述的半导体量子振荡器件， 其特 于： 所述施加 电压的装置包括分别位于所述两个载流子振荡区不和隧穿注入区相接一側 的两个接触电极， 外加电压通过所述两个接触电极而加到所述栽流子振荡 区上。
3. 根据权利要求 1所述的半导体量子振荡器件， 其特征在于： 所述隧穿 注入区和载流子振荡区由禁带宽度不同的多个半导体外延层按特定顺序排 列得到的异质结构构成。
4. 根据权利要求 1所述的半导体量子振荡器件， 其特征在于： 所述的隧 穿注入区和载流子振荡区由非有意掺杂的半导体层构成。
5. 根据权利要求 1所述的半导体量子振荡器件， 其特征在于： 所述的隧 穿注入区由一耦合双量子阱结构构成， 两个阱外侧的区域既限定量子阱的 外边界又同时构成两个载流子振荡区。
6. 根据权利要求 5所述的半导体量子振荡器件， 其特 于： 所述施加 电压的装置包括分别位于所述两个载流子振荡区不和隧穿注入区相接一側 的两个接触电极， 外加电压通过所述两个接触电极而加到所述栽流子振荡 区上。
7. 根据权利要求 6所述的半导体量子振荡器件， 其特征在于： 所述的两 个接触电极包括导电类型分别为 n型和 p型的两个接触区， 所述的施加电压 的装置把正极， 的电压加在包 型接触区的接触电极上。
8. 根据权利要求 5所述的半导体量子振荡器件， 其特征在于： 所述的振 荡区由短周期超晶格构成。
9. 一种由如权利要求 1 所述的半导体量子振荡器件构成的远红外激光 器， 进一步包括将所述的半导体量子振荡器所发射的远红外辐射耦合到振 荡器内的装置。
PCT/CN1998/000049 1997-04-10 1998-03-23 Oscillateur quantique a semi-conducteur WO1998045882A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP98910573A EP1009034A4 (en) 1997-04-10 1998-03-23 SEMICONDUCTOR QUANTUM OSCILLATOR ARRANGEMENT
US09/402,709 US6472683B1 (en) 1997-04-10 1998-03-23 Semiconductor quantum oscillation device
JP54220998A JP2001522527A (ja) 1997-04-10 1998-03-23 半導体量子発振装置
AU64936/98A AU6493698A (en) 1997-04-10 1998-03-23 Semiconductor quantum oscillation device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN97110353.4 1997-04-10
CN97110353.4A CN1195895A (zh) 1997-04-10 1997-04-10 半导体量子振荡器件

Publications (1)

Publication Number Publication Date
WO1998045882A1 true WO1998045882A1 (fr) 1998-10-15

Family

ID=5171385

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN1998/000049 WO1998045882A1 (fr) 1997-04-10 1998-03-23 Oscillateur quantique a semi-conducteur

Country Status (6)

Country Link
US (1) US6472683B1 (zh)
EP (1) EP1009034A4 (zh)
JP (1) JP2001522527A (zh)
CN (2) CN1195895A (zh)
AU (1) AU6493698A (zh)
WO (1) WO1998045882A1 (zh)

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6958497B2 (en) * 2001-05-30 2005-10-25 Cree, Inc. Group III nitride based light emitting diode structures with a quantum well and superlattice, group III nitride based quantum well structures and group III nitride based superlattice structures
US6829269B2 (en) * 2002-05-21 2004-12-07 University Of Massachusetts Systems and methods using phonon mediated intersubband laser
US7158545B2 (en) * 2003-09-12 2007-01-02 Massachusetts Institute Of Technology Terahertz lasers and amplifiers based on resonant optical phonon scattering to achieve population inversion
US20050058166A1 (en) * 2003-09-12 2005-03-17 Qing Hu Metal waveguides for mode confinement in terahertz lasers and amplifiers
US7224041B1 (en) 2003-09-30 2007-05-29 The Regents Of The University Of California Design and fabrication of 6.1-Å family semiconductor devices using semi-insulating A1Sb substrate
WO2005050722A1 (en) * 2003-11-17 2005-06-02 The Regents Of The University Of California DESIGN AND FABRICATION OF 6.1- Å FAMILY SEMICONDUCTOR DEVICES USING SEMI-INSULATING AlSb SUBSTRATE
CN100359707C (zh) * 2004-04-16 2008-01-02 氮化物半导体株式会社 氮化镓系发光器件
TWI315585B (en) * 2005-04-28 2009-10-01 Chung Shan Inst Of Science Resonant tunneling quantum dot device
JP5171539B2 (ja) * 2007-11-29 2013-03-27 キヤノン株式会社 共鳴トンネル構造体
KR100961109B1 (ko) * 2008-02-11 2010-06-07 삼성엘이디 주식회사 ＧａＮ계 반도체 발광소자
US8203127B2 (en) * 2008-05-06 2012-06-19 The United States Of America, As Represented By The Secretary Of The Army Terahertz radiation device using polar semiconductor materials and method of generating terahertz radiation
FR2980642B1 (fr) * 2011-09-23 2014-11-14 Centre Nat Rech Scient Dispositif a super-reseau semiconducteur fonctionnant dans le domaine de frequences terahertz
JP5953840B2 (ja) * 2012-03-13 2016-07-20 富士通株式会社 半導体装置及び受信機
CN104465913B (zh) * 2014-11-26 2017-06-16 西安电子科技大学 具有双InGaN子量子阱的共振隧穿二极管及其制作方法
CN109524453B (zh) * 2018-10-22 2022-03-29 杭州电子科技大学 一种GaN基高压整流共振隧穿二极管
CN114993360A (zh) * 2022-06-07 2022-09-02 电子科技大学 一种通过声子相干性进行精密测量的方法与装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01223775A (ja) * 1988-03-03 1989-09-06 Toshiba Corp 二重障壁共鳴トンネル素子
JPH01278068A (ja) * 1988-04-28 1989-11-08 Nippon Telegr & Teleph Corp <Ntt> 半導体装置
EP0690516A1 (en) * 1994-06-30 1996-01-03 Sharp Kabushiki Kaisha Semiconductor light emitting device
US5588015A (en) * 1995-08-22 1996-12-24 University Of Houston Light emitting devices based on interband transitions in type-II quantum well heterostructures
US5659180A (en) * 1995-11-13 1997-08-19 Motorola Heterojunction interband tunnel diodes with improved P/V current ratios

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3626328A (en) 1969-04-01 1971-12-07 Ibm Semiconductor bulk oscillator
US3626257A (en) 1969-04-01 1971-12-07 Ibm Semiconductor device with superlattice region
US4198644A (en) * 1978-06-09 1980-04-15 The United States Of America As Represented By The Secretary Of The Army Tunnel diode
US4371884A (en) * 1981-01-23 1983-02-01 The United States Of America As Represented By The Secretary Of The Army InAs-GaSb Tunnel diode
JPS61161774A (ja) * 1985-01-10 1986-07-22 Nec Corp ダイオ−ド
US4667211A (en) * 1985-09-05 1987-05-19 The United States Of America As Represented By The Secretary Of The Army Millimeter wave-infrared bloch oscillator/detector
US5132746A (en) * 1991-01-04 1992-07-21 International Business Machines Corporation Biaxial-stress barrier shifts in pseudomorphic tunnel devices

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01223775A (ja) * 1988-03-03 1989-09-06 Toshiba Corp 二重障壁共鳴トンネル素子
JPH01278068A (ja) * 1988-04-28 1989-11-08 Nippon Telegr & Teleph Corp <Ntt> 半導体装置
EP0690516A1 (en) * 1994-06-30 1996-01-03 Sharp Kabushiki Kaisha Semiconductor light emitting device
US5588015A (en) * 1995-08-22 1996-12-24 University Of Houston Light emitting devices based on interband transitions in type-II quantum well heterostructures
US5659180A (en) * 1995-11-13 1997-08-19 Motorola Heterojunction interband tunnel diodes with improved P/V current ratios

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP1009034A4 *

Also Published As

Publication number Publication date
CN1195895A (zh) 1998-10-14
EP1009034A1 (en) 2000-06-14
CN1117399C (zh) 2003-08-06
JP2001522527A (ja) 2001-11-13
US6472683B1 (en) 2002-10-29
AU6493698A (en) 1998-10-30
EP1009034A4 (en) 2002-11-27
CN1252167A (zh) 2000-05-03

Similar Documents

Publication Publication Date Title
WO1998045882A1 (fr) Oscillateur quantique a semi-conducteur
Nagarajan et al. High speed quantum-well lasers and carrier transport effects
US7843981B2 (en) Quantum cascade laser
US6751243B2 (en) Semiconductor device with quantum dots having high carrier injection efficiency, its manufacture method, and semiconductor laser device
JPH0691298B2 (ja) 半導体光素子、半導体レーザ及び半導体レーザを動作させる方法
Alexander et al. Systematic Study of the Effects of Modulation p-Doping on 1.3-$\mu {\hbox {m}} $ Quantum-Dot Lasers
Suemune et al. Superconductor-based quantum-dot light-emitting diodes: role of cooper pairs in generating entangled photon pairs
US4816878A (en) Negative resistance semiconductor device
JPH04230043A (ja) エネルギーバンド平坦化変調ドープ型量子井戸構造
Mu et al. Theoretical investigation of mid-infrared interband cascade lasers based on type II quantum wells
US6285697B1 (en) Semiconductor laser component
US20080151956A1 (en) Interband tunneling intersubband transition semiconductor laser
North et al. The two-dimensional lateral injection in-plane laser
Kunold et al. Photoluminescence transitions in semiconductor superlattices. Theoretical calculations for InGaN blue laser device
JP2002368342A (ja) 多重量子井戸半導体素子
Brown High-speed resonant-tunneling diodes
Itskevich et al. X-valley-related donor states and resonant tunneling in a single-barrier diode
Vinoslavskii et al. Effect of barrier width between GaAs/InGaAs/GaAs double coupled quantum wells on bipolar transport and terahertz radiation by hot carriers in lateral electric field
KR100818632B1 (ko) 부밴드 천이 반도체 레이저
EP0759640B1 (en) Semiconductor superlattice oscillator and methods of manufacturing and operating the same
JPH11354884A (ja) 半導体レーザ及び半導体レーザの製造方法
Carnahan et al. Γ‐X intervalley tunneling in InAs/AlSb resonant tunneling diodes
JP2001085795A (ja) 半導体素子および半導体発光素子
JP2556288B2 (ja) 半導体レーザ
Brandl et al. Millimeter wave generation by a self-sustained current oscillation in an InGaAs/InAlAs superlattice

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 98804016.6

Country of ref document: CN

AK Designated states

Kind code of ref document: A1

Designated state(s): AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GE GH GM GW HU ID IL IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT UA UG US UZ VN YU ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW SD SZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN ML MR NE SN TD TG

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
ENP Entry into the national phase

Ref document number: 1998 542209

Country of ref document: JP

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 09402709

Country of ref document: US

WWE Wipo information: entry into national phase

Ref document number: 1998910573

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWP Wipo information: published in national office

Ref document number: 1998910573

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: CA

WWR Wipo information: refused in national office

Ref document number: 1998910573

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 1998910573

Country of ref document: EP