JP2007503710A - Semiconductor device and method - Google Patents

Abstract

A bipolar transistor capable of operating at very high speeds and a method thereof that can potentially exceed the already reached speeds.
A method and device for generating controllable light radiation from a bipolar transistor is disclosed. It also provides a bipolar transistor having the following steps: emitter, base, and collector regions, providing an electrode that couples the electrical signal with the emitter, base, and collector regions, and inducing against the disadvantages of natural radiation A method for increasing the speed of a bipolar transistor is also disclosed that includes adapting the base region to enhance radiation, thereby reducing the carrier recombination lifetime of the base region.
[Selection] Figure 1

Description

  The present invention relates to high speed semiconductor devices and methods, and more particularly to semiconductor devices and methods capable of producing controlled light emission and simultaneously amplifying electrical signals.

  Part of the background in this regard is the development of light emission based on direct bandgap semiconductors such as III-V semiconductors. Such devices, including light emitting diodes and laser diodes, are widely used commercially.

  Another part of this background is the development of wide bandgap semiconductors to achieve the high minority carrier injection efficiency of devices known as heterojunction bipolar transistors (HBTs), which was first proposed in 1948. (See, eg, US Pat. No. 2,569,376; see also “Theory Of A Wide-Gap Emitter For Transistors” in Proceedings Of The IRE, 45, 1535-1544 (1957) by H. Kroemer. thing). These transistor elements can operate at very high speeds. It has recently been shown that InP HBTs operate at speeds above 500 GHz.

  It is an object of the present invention to provide a bipolar transistor device and method thereof that can operate at very high speeds that can potentially even exceed the speeds already reached. It is a further object of the present invention to provide an element and method for generating controlled light radiation and to provide an element capable of simultaneous control of light output and electrical output.

  One aspect of the invention includes a direct bandgap heterojunction transistor that exhibits light emission from the base layer. Modulation of the base current generates modulated light radiation. As used herein, “light” means optical radiation in or outside the visible range.

  A further aspect of the invention includes the operation of the three ports of the light emitting HBT. Both the natural light emission and the electrical signal output are modulated by a signal applied to the base of the HBT.

  Another aspect of the present invention involves incorporating stimulated radiation that is useful in the base layer of a bipolar transistor (eg, bipolar junction transistor (BJT) or heterojunction bipolar transistor (HBT)) to increase transistor speed. Natural radiative recombination lifetime is an intrinsic limitation of bipolar transistor speed. In the form of the invention, the base layer of the bipolar transistor is adapted to enhance stimulated emission (or stimulated recombination) against the disadvantages of natural radiation, thereby reducing recombination lifetime and increasing transistor speed. Let In this aspect of the invention, at least one layer exhibiting a quantum size effect is provided in the base layer of the bipolar transistor, preferably a layer of preferably undoped or lightly doped preferably quantum wells or quantum dots. The Preferably, at least a portion of the base layer including at least one layer exhibiting a quantum size effect is highly doped and is made of a band gap material wider than said at least one layer. At least one quantum well, or layer of quantum dots, enhances inductive recombination and reduces radiative recombination lifetime within a high gap of highly doped material. Two-dimensional electron gas (“2-DEG”) increases the carrier concentration of the quantum well or quantum dot layer, thereby improving the mobility of the base region. By improving the base resistance, the base thickness can be reduced along with the reduction of the base transportation time. These advantages in speed are applicable to high speed bipolar transistors where light radiation is utilized and / or to high speed bipolar transistors where light radiation is not utilized. In light-emitting bipolar transistor devices, such as heterojunction bipolar transistors of indirect band gap materials, the use of one or more layers exhibiting quantum size effects can also enhance light emission and customize the device's emission wavelength characteristics. It is advantageous.

  In one preferred embodiment in this regard, quantum well layers and / or quantum dot layers that exhibit quantum size effects preferably have a thickness of about 100 angstroms or less.

  According to one embodiment of the present invention, the method provides a heterojunction bipolar transistor including the following steps to generate controllable light emission from a semiconductor device: collector, base, and emitter regions; And applying an electrical signal across the terminals coupled to the collector, base, and emitter regions to cause light emission due to radiative recombination of the base region. In the form of this embodiment, applying the electrical signal includes modulating the light output by applying a collector-emitter voltage and applying a modulation base current.

  According to another embodiment of the present invention, the element has an input port for receiving an electrical input signal, an electrical output port for outputting an electrical signal modulated by the input signal, and light for outputting an optical signal modulated by the input signal. The device includes a heterojunction bipolar transistor device that includes a collector, base, and emitter region, the input port includes an electrode coupled to the base region, and the electrical output port includes a collector region and an emitter region. And the optical output port includes optical coupling with the base region.

  According to a further embodiment of the present invention, a semiconductor laser includes a heterojunction bipolar transistor structure including a collector, base and emitter of direct bandgap material, an optical resonant cavity surrounding at least a portion of the transistor structure, and a laser from the transistor structure. It is described as including means for combining the electrical signal with the collector, base, and emitter regions to cause radiation.

  According to another embodiment of the present invention, the method provides the following steps to increase the speed of the bipolar transistor: a bipolar transistor having an emitter, base, and collector region; And providing an electrode for coupling the collector region, and adapting the base region to enhance stimulated emission against the disadvantages of natural radiation, thereby reducing the carrier recombination lifetime of the base region It is explained that there is. In the form of this embodiment, the step of adapting the base region in order to enhance the stimulated emission against the disadvantages of natural radiation comprises at least one layer exhibiting a quantum size effect in the base region, preferably undoped or Providing a lightly doped, preferably quantum well and / or quantum dot layer.

  According to one aspect of the present invention, a plurality of spaced quantum size regions (eg, quantum wells and / or quantum dots) having different thicknesses are provided in the base region of the bipolar transistor and pass through the base region in a certain direction. It is used to advantageously advance carrier transportation. As an example, the base region is provided with several spaced quantum size regions of different thicknesses, the thickness of which is rated from the thickest near the collector to the thinnest near the emitter . The injected electrons are trapped in the small well, tunneled in the next large well, and then the next large tunnel, etc., and tunneled and relaxed to the lowermost state of the largest well, with the largest well closest to the collector And recombine. The well arrangement facilitates carrier transport in a certain direction from the emitter to the collector. Maximum recombination and maximum luminous intensity arise from the largest well as close as possible to the collector, which is in an advantageous position for reasons such as optical cavities. Carriers diffuse “down” in energy, ie towards thicker wells. The asymmetric well size improves the direction and speed of carrier transport. In embodiments such as light emitting HBT, both light emission and device speed are improved.

  Additional features and advantages of the present invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.

FIG. 1 shows a device according to an embodiment of the invention, which can be used in carrying out an embodiment of the method of the invention. A substrate 105 is provided and the following layers are disposed thereon: subcollector 110, collector 130, base 140, emitter 150, and cap layer 160. Also shown is collector metallization (ie, electrode) 115, base metallization 145, and emitter metallization 165. A collector lead 117, a base lead 147, and an emitter lead 167 are also shown. In the form of this embodiment, the layer is grown by MOCVD, and the collector layer 130 comprises 3000 Å thick n-type GaAs, n = 2 × 10 ¹⁶ cm ⁻³ , and the base layer 140 is 600 Å thick p ⁺ . Carbon doped and mixed grade InGaAs (1.4% In), p = 4.5 × 10 ¹⁹ cm ⁻³ , emitter layer 150 is 800 Å thick n-type InGaP, n = 5 × 10 ¹⁷ It includes cm ^-3, and the cap layer comprises a 1000 angstrom thick ^{n + InGaAs, n = 3 ×} 10 19 cm -3.

  The present embodiment includes an e-beam defined Ti / Pt / Au emitter contact (165), self-aligned emitter etch process, self-aligned Ti / Pt / Au base metal deposition, base-collector etch process, and collector metal. Adopt manufacturing process procedures including deposition. A bisbenzocyclobutene (BCB) based etch back process is incorporated for “back end” manufacturing (ie, to make contact between the electrode and the tip of the transistor).

For conventional PN junction diode operation, the recombination process is based on both electrons injected from the n side and holes injected from the p side, which can be speed limited in the bimolecular recombination process. In the case of HBT light emission, the “hole” concentration of the base is so high that when electrons are injected into the base, they recombine quickly (bimolecular). The base current simply resupplyes the holes via relaxation to neutralize the charge imbalance. For a heterojunction bipolar transistor (HBT), the base current can be divided into seven components. That is, (1) hole injection into the emitter region (i _Bp ), (2) exposed surface recombination current of the external base region (i _Bsurf ), (3) base ohmic contact recombination current (i _Bcont ), ( 4) Space charge recombination current (i _Bscr ), (5) Bulk base non-radiative recombination current (i _BHSR ) by Hall Shockley Read process (HSR), (6) Bulk base Auger recombination Current (i _BAug ), and (7) bulk-based radiative recombination current (i _Brad ).

For relatively efficient HBTs with passivation of ledges on the exposed base region, the surface recombination current is significantly reduced. Thus, base current and recombination lifetime are estimated primarily as bulk HSR recombination, Auger process, and radiative recombination. The base current represented by the following equation (1) is
i _B = i _BHSR + i _BAUG + i _Brad = qA _E Δn / τ _n (1)
As follows: excess minority carriers Δn in the neutral base region, emitter region A _E , charge q and base recombination lifetime τ _n . The overall base recombination lifetime τ _n is
τ _n = (1 / τ _HSR + 1 / τ _AUG + 1 / τ _rad ) ⁻¹ (2)
As related to the individual recombination components of Hall Shockley Reed τ _HSR , Auger τ _AUG , and radiative recombination τ _rad .

The light emission intensity ΔI in the base is proportional to i _Brad , and minority carrier electrons (np−n _i ² ) with majority holes exceeding the intrinsic carrier concentration in the neutral base region shown in equation (3) below. and associated with radiative recombination process rate B, this time the hole concentration is estimated to be equal to the base dopant concentration N _B. The radioactive base current expressed by equation (3) is
i _Brad = qA _E B (np-n _i ² ) = qA _E Bnp = qA _E Δn (BN _B ) = qA _E Δn / τ _rad (3)
As a function of excess minority carriers Δn in the neutral base region and the base recombination lifetime τ _rad .

  For fast HBT, it is easy to predict that the base recombination lifetime will be less than half of the overall response delay time. Therefore, the optical recombination process at the base should be at least twice as fast as the HBT. In other words, the HBT speed is extremely fast and limited.

FIG. 2 shows a top view of the device layout and FIG. 3 shows a silicon CCD of an HBT test device manufactured at 1 × 16 μm ² with light emission (white dots) from the base layer under normal operation of the transistor. Figure from a microscope is shown.

  In normal transistor operation, one of the three terminals of the transistor is common to both the input circuit and the output circuit. This results in the familiar structures known as common emitter (CE), common base (CB), and common collector (CC). A common terminal (often a ground reference) can be combined with one of the remaining two terminals or another. Each pair is called a port, and the two pairs for any structure are called a two-port network. The two ports are usually identified as input ports and output ports. According to this feature shown in FIG. 4, a third port, the light output port, is provided, which is based on (recombination-radiation) radiation from the base layer of the HBT light emitter according to an embodiment of the invention. For example, for the HBT of FIG. 1 operating with a common emitter structure (see FIG. 4), when an electrical signal is applied to the input port (port 1), the electrical output with signal amplification at port 2 and A light output with signal modulation of the light emission occurs simultaneously at port 3.

The common emitter output characteristics of the test version of the device of FIGS. 1 and 2 are shown in FIG. The DC beta gain is β = 17 with i _b = 1 mA. For i _b = 0 mA (i _c = 0 mA), no light emission is observed using a silicon CCD detector. For i _b = 1 mA (i _c = 17.3 mA), weak light emission is observed from the base layer. Stronger light emission is observed for i _b = 2 mA (i _c = 33 mA) and stronger light emission is observed for i _b = 4 mA (i _c = 57 mA). The spontaneous light emission due to the radiative recombination of the HBT base in transistor operation is clearly evident.

An output light modulation test was performed on this embodiment. A pattern generator (Tektronix function generator) generates an AC signal with a peak-to-peak amplitude of 1V. The bias tee combines this AC signal with a 1.1V DC bias voltage from the DC supply. The InGaP / GaAs HBT turn-on voltage is V _BE = 1.5V. The radiation area of the HBT transistor (base area) is less than 1 μm × 2 μm. Light from a small aperture (most HBT light is confusing in this test) is coupled to a multimode fiber probe with a core diameter of 25 μm. The light is fed into a Si APD detector with a 20 dB linear amplifier. The sampling oscilloscope displays both the input modulation signal and the output optical signal. The light emission wavelength is approximately 885 nm for a mixed grade InGaAs base (1.4% In). FIG. 6 shows the input (lower trace) reference and output (upper trace) optical waveforms when the HBT is modulated at 1 MHz (FIG. 6A) and further at 100 KHz (FIG. 6B). The output signal has a peak-to-peak amplitude of 375 μV at 1 MHz and a peak-to-peak amplitude of 400 μV at 100 KHz. These data indicate that the output optical signal tracks the input signal, clearly indicating that the HBT is a light emitting transistor (LET) operating at transistor speed.

Output peak-to-peak amplitude Vpp which is directly proportional to the light emission intensity [Delta] I _out as a function of base current, is shown in FIG. Non-linear operation is due to beta compression due to the fact that heating and device geometry are still not optimized for light emission (and lateral bias effects). Nevertheless, these measurements, ΔI _out (light intensity) vs. Δi _b (i _b = 0 mA to 5 mA), demonstrate HBT as a three-terminal controllable light source.

  Of course, other structures and material systems can be used, including, for example, GaAs and GaN based HBTs, or other direct bandgap material systems.

  GaAsSb is for a more advantageous type II bandgap configuration (holes are sealed and electrons are not sealed) at the base-collector (or emitter) junction (as shown at the bottom of FIG. 8). Proposed as an InGaAs alternative to the base of InP HBTs. Type II InP-based HBTs (as shown at the bottom of FIG. 8) have large valence band discontinuities, so there is excellent hole blocking at the emitter (R. Bhat, W.-P. Hong, C. Canau, MA Koza, C.-K. Nguyen, and Appl.Phys.Lett., 68,695 (1995), T. McDermott, ER Gertner, S. Gosami. (See Appl. Phys. Lett. 58, 1386 (1996) by Pittman, C. W. Seabury, and M. F. Chang). For all InP collectors, Type II InP / GaAsSb DHBTs (double HBTs) are expected to have better thermal properties and higher breakdown voltages than Type I InP / InGaAs DHBTs. InP / GaAsSb DHBTs have been reported to reach a cut-off frequency in excess of 300 GHz (Dvorak, CR Bolognesi, OJ Pitts, and IEEE Watsons Elect. Dev. Lett. 22, 361 (2001)). FIG. 8 shows a band diagram of a Type II InP / GaAsSb / InP double heterojunction bipolar transistor (DHBT), whose physical structure and operation is similar to that of FIGS. 1 to 4 described above. In this example, the light emitting transistor has a 30 nm p-type GaAsSb base that generates a recombination-radiation signal in normal transistor operation (with the collector reverse biased).

Type II InP / GaAsSb DHBT is fabricated with an emitter area of 120 × 120 μm ² and a current gain β = 38. Under normal transistor bias, light emission is obtained at a wavelength centered at λ _peak = 1600 nm from a base region of 30 nm GaAs _0.51 Sb _0.49 carbon doped with 4e19 cm ⁻³ . In this example, a Type II HBLET 3-port operation using amplified electrical and optical outputs simultaneously with signal modulation at 10 kHz (limited by the bandwidth of the germanium PIN detector) is shown.

The layer structure of this example is grown by MOCVD on a semi-insulating, iron-doped InP substrate. HBLET was Si-doped with 3 × e16 cm ⁻³ Si-doped 150 nm InP collector, 4e19 cm ⁻³ C-doped 30 nm GaAs _0.51 Sb _0.49 base, 5 × 10 ¹⁷ cm ⁻³ Includes 20 nm InP and 40 nm In _0.53 Ga _0.47 As emitter contact cap, n = 2 × 10 ¹⁹ cm ⁻³ . DHBT devices are manufactured using standard mesa processes. As shown in FIG. 8, the energy band diagram of a type II light emitting InP (n) / GaAsSb (p ⁺ ) / InP (n) double heterojunction bipolar transistor (DHBT) is model solid theory (V. calculated using the Physical Review B 39,1871 (1989) by de Walle. The energy gap for the GaAs _0.51 Sb _0.49 base layer involves a conduction band discontinuity ΔE _v = 0.15 eV and a valence band discontinuity ΔE _v = 0.57 eV between the InP collector (or emitter) and the GaAsSb base. 0.72 eV. The energy band diagram of FIG. 8 includes an emitter-base junction where the DHBT is forward biased at V _eb = 0.7V and an emitter-collector junction that is reverse biased at V _ec = 1.2V. It shows a common emitter (CE) structure in normal transistor mode operation.

The common emitter output characteristics of the described type II transistor with a 120 × 120 μm ² emitter region, ie the collector current versus collector-emitter voltage (IV) curve, is shown in FIG. dc beta gain _{(β = Δi c / Δi b} ) _is beta = 5 with i b = 1 _mA, increases as i b = 3mA at β = _16, i b = 5mA at beta = 38. From the measured Gummel plot of the transistor, the ideal coefficient for low base current is approximately 1.9, which represents a significant number of traps in the base-emitter space charge region (SCR). The ideal factor for high base current is 1.3, indicating further surface recombination as soon as the SCR trap is full. For a small 30 × 30 μm ² emitter DHBT, the dc beta gain (β = Δi _c / Δi _b ) is β = 25 (large) when i _b = 1 mA because the number of SCR traps is This is because it is proportional to the emitter region of DHBT. For the 120 × 120μm ² HBT, current gain cutoff frequency _{f t} is measured at 800 MHz. The power gain cutoff frequency f _max is 300 MHz. For the same layer structure with smaller emitters of 0.8 × 8 μm ² , the HBT cutoff frequency is f _t = 181 GHz and f _max = 152 GHz.

The base current is relatively small for Type II DHBTs with large emitter areas such as 120 × 120 μm ² due to surface recombination. As such, base current is primarily estimated as non-radiative Hall Shockley Reed (HSR) recombination in the emitter-base space charge region and radiative recombination in the base neutral region. For the emission process in the base region of the HBT, the light emission intensity ΔI is proportional to the component of the base current that supplies the radiative recombination i _Brad , which is the excess (injected) minority carrier Δn, charge in the neutral base region q is proportional to the emitter region A _E and inversely proportional to the radiative recombination lifetime τ _rad . For common emitter (CE) type II DHBT light emission, the base hole concentration is so high that electrons injected into the base recombine quickly (bimolecularly). The base current only resupply holes through relaxation to neutralize charge imbalance.

An ultrasensitive germanium PIN detector (Model E1-L from Edinburg Instruments) with a very high response power of 5 × 10 ⁹ V / W was used to detect HBLET light radiation. FIG. 10 shows a substantially linear relationship of light emission intensity (recombination emission) as a function of base current. The light emission wavelength of the element operating as an HBT is centered around λ _peak = 1600 nm and coincides with the interband recombination transition of GaAs _x Sb _1-x . The shift of peak light emission from the lattice-matched (GaAs _0.51 Sb _0.49 ) gap (E _g = 0.72 eV, λ _peak = 1722 nm) in the short wavelength direction is due to an alloy that does not match the InP lattice constant. It is supposed to be. The spread light radiation extends from 1450 nm to 1750 nm mainly due to alloy scattering of the GaAsSb base layer.

A pattern generator that generates an AC input signal at 10 kHz was used for testing light output modulation. 120 × 120 μm ² DHBT recombination radiation was fed into a germanium PIN detector integrated with a JFET preamplifier. The coupling has a very high response power of 5 × 10 ⁹ V / W, but of course a slow response of 1 ms to 2 ms which limits the measurement (10 kHz). FIG. 11 shows traces from a four channel sampling oscilloscope and illustrates the operation of three ports. The top trace (a) is with the input signal modulated at 10 kHz (port 1) and the second trace (b) is biased with I _B = 2 mA and V _CE = 2V (common emitter) DHBT Output voltage (port 2). The third trace (c) shows the optical output signal (port 3) modulated at 10 kHz. These data show the operation of the three ports of a Type II DHBT biased with a common emitter structure with a GaAsSb alloy base region.

  FIG. 12 illustrates the use of a three-terminal light emitting HBT 810 in conjunction with a reflective cup 820 that enhances light collection and directionality.

  FIG. 13 shows a three-terminal light emitting HBT 910 in a lateral cavity, represented by 920, that operates as a lateral gain guided laser. The lateral cavity is defined, for example, by a cleaved edge on or near the light emitting region.

  One aspect of the invention is to employ stimulated radiation that benefits the base layer of a bipolar transistor (eg, bipolar junction transistor (BJT) or heterojunction bipolar transistor (HBT)) to increase transistor speed. Including. Natural radiative recombination lifetime is an intrinsic limit of bipolar transistor speed. In the form of the present invention, the base layer of the bipolar transistor is adapted to enhance stimulated radiation (or stimulated recombination) against the loss of spontaneous radiation, thereby reducing recombination lifetime and increasing transistor speed. . In the form of this aspect of the invention, at least one layer exhibiting a quantum size effect is provided in the base layer of the bipolar transistor, ie preferably a layer of quantum wells or quantum dots, preferably undoped or lightly doped. . Preferably, at least a portion of the base layer including at least one layer exhibiting a quantum size effect is highly doped and made of a wider band gap material than the at least one layer. At least one quantum well, or layer of quantum dots, enhances inductive recombination and reduces radiative recombination lifetime within a high gap of highly doped material. Two-dimensional electron gas (“2-DEG”) increases the carrier concentration of the quantum well or quantum dot layer, thereby improving the mobility of the base region. Improved base resistance allows for a reduction in base thickness and concomitant reduction in base transport time. These advantages in speed can be applied with high speed bipolar transistors where light radiation is utilized and / or with high speed bipolar transistors where light radiation is not utilized. In light emitting bipolar transistor devices such as heterojunction bipolar transistors of indirect band gap materials, the use of one or more layers exhibiting quantum size effects can enhance light emission and customize the emission wavelength characteristics of the device. Is also beneficial. In some embodiments, doped or highly doped quantum size regions are also utilized.

FIG. 14A illustrates the use of one or more quantum wells 141, 142 in the base region 140 of the device of FIG. 1 (or other embodiments), which have improved device speed, modulation characteristics. To reinforce the recombination process and / or to adjust the spectral characteristics of the device. In one preferred embodiment of this type of the invention, the quantum well (and / or dot-see below) is made of a lower bandgap than the surrounding base layer (140) material and is undoped or lightly doped. (For example, approximately 10 ¹⁶ cm ⁻³ or less). The surrounding base layer (140) material is highly doped (eg, uniformly doped or delta doped with at least about 10 ¹⁸ cm ⁻³ for p-type or at least about 10 ¹⁷ cm ⁻³ for n-type). ) In one preferred embodiment, the quantum well (or dot) layer has a thickness of approximately 100 angstroms or less.

  As shown elsewhere herein, a cavity with a reflector can be laterally (eg, FIG. 13) or longitudinally (eg, FIGS. 27 and 28) to obtain controlled laser operation of the light emitting HBT. Available. As mentioned above, enhancing the stimulated emission reduces the recombination lifetime and increases the operating speed. If desired, a reflector (eg, reflector 920 in FIG. 13 or a reflective layer in FIGS. 27 and 28) can be used instead of partially reflecting (as in the case of the right reflector 920 in FIG. 13). ) Maximize the reflected radiation that can be totally reflected, remove output radiation through the reflector and enhance the stimulated radiation.

  FIG. 14B illustrates the use of one or more regions of quantum dots 143, 144 in the base region 140 of the device of FIG. 1 (or another embodiment), these quantum dot regions being improved device speeds. Operate to enhance the recombination process for modulation characteristics and / or to adjust the spectral characteristics of the element.

Examples of structures and material systems with lightly doped or undoped quantum wells in a highly doped p ⁺ base are shown in FIGS. 15-22. In FIG. 15, regions and metallizations having similar reference numbers to the regions and metallizations of FIG. 1 typically correspond to structures excluding regions 141 that are quantum well layers. An example of a Type I InP double heterojunction bipolar transistor (DHBT) includes the following components 105: semi-insulating InP substrate 110: n ⁺ InGaAs subcollector 115: collector metallization 130: n ⁻ InP collector 140: p ⁺ InP base 141: undoped InGaAs QW in base
147: Base metallization 150: n InP emitter 160: n ⁺ InGaAs emitter cap 165: with emitter metallization.
The band diagram for this example structure is V _BE =. 7V and V _BC =. Biased at 5V and shown in FIG. Examples of variations on this type I structure (DHBT or SHBT) include the following components 130: n InGaAsP collector 140: p ⁺ InGaAsP base 1411: undoped InGaAs QW in the base
Includes 150: n InP emitter.

Examples of Type II InP DHBTs include the following components 105: semi-insulating InP substrate 110: n ⁺ InGaAs subcollector 115: collector metallization 130: n ^- InP collector 140: p ⁺ InP base 141: within the base Undoped InGaAs QW
147: Base metallization 150: n InP emitter 160: n ⁺ InGaAs emitter cap 165: with emitter metallization.
The band diagram for this example structure is V _BE =. 7V and V _BC =. Biased at 5V and shown in FIG. Examples of variations on this Type II structure (DHBT or SHBT) include the following components 130: n InP collector 140: p ⁺ GaAsSb base 141: undoped InGaAs QW in the base
Includes 150: n InP emitter.
The band diagram for this example structure is V _BE =. 7V and V _BC =. Biased at 5V and shown in FIG.

Examples of Type I GaAs SHBTs or DHBTs include the following components 130: n GaAs collector 140: p ⁺ GaAs base 1411: undoped InGaAs QW in the base
150: InGaP emitter or 130: N GaAs collector 140: p ⁺ GaAs base 141: undoped InGaAs QW in base
150: Includes an AlGaAs emitter. Other material systems such as GaN based devices can also be used.

  19, 20 and 21 show further band diagrams for the quantum wells of the HBT in the base.

FIG. 19 shows the structure and band diagram for HBT with InP emitter and collector and InGaAs subcollector. The base region comprises undoped GaAsSb quantum wells (enhancing hole recombination) and heavily doped (p ⁺ ) GaAsSb including p ⁺ InGaAs quantum wells (enhancing electron recombination).

FIG. 20 again shows the structure and band diagram for an HBT with an InP emitter and collector and an InGaAs subcollector. The base region comprises heavily doped (p ⁺ ) GaAsSb including two undoped GaAsSb quantum wells and two p ⁺ InGaAs quantum wells. In FIG. 21 (again having the same structure except for the base), the base region includes three p ⁺ InP quantum wells with two interfering undoped InGaAs quantum wells. In addition to different well configurations, different well sizes can be incorporated.

As mentioned above, one or more quantum wells are incorporated to serve in the base region of the HBT. The following example illustrates gigahertz operation of a light emitting transistor with two thin In _1-x Ga _x As (x = 85%) quantum wells (QWs) operating as electron traps (for ideal situations terahertz It is expected to be close to operation) and thus serves as a QW-collector recombination radiation source embedded in a GaAs base layer of InGaP / GaAs HBT.

A band diagram of a light emitting transistor with two thin InGaAs quantum wells in a heavily doped base, namely an InGaP (n) / GaAs (p ⁺ ) / GaAs (n) single heterojunction bipolar transistor (SHBT) is shown. 22 and its layer structure is apparent from the diagrams and the description above and following. In a common emitter structure for normal transistor mode operation, the base-emitter junction is forward biased and the base-collector junction is reverse biased. Light emission from the base at two different wavelengths is expected for interband recombination transitions involving both GaAs bases and InGaAs QWs. The layer structure for this exemplary device is grown by MBE and is 600 コ レ ク タ GaAs collector with n = 2 × 10 ¹⁶ cm ⁻³ , p = 4 × 10 ¹⁹ cm ⁻³ and 300 カ ー ボ ン carbon doped GaAs. Two 50 _- inch In _1-x Ga _x As (x = 85%) quantum wells (QWs) embedded in the base, 300-inch InGaP emitter with n = 5 × 10 ¹⁷ cm ⁻³ , 300-inch GaAs emitter cap, And a 300 Ｉｎ InGaAs emitter contact cap with n = 3 × 10 ¹⁹ cm ⁻³ . Under the collector, a small nine-period 621 Å Al _0.2 Ga _0.8 As + 725 ０．９ Al _0.95 Ga _0.15 As distributed to the Bragg reflector is used to facilitate longitudinal leakage of recombination radiation. Included.

For common emitter (CE) HBT light emission, the base hole concentration is so high that when electrons are injected into the base, they recombine quickly (bimolecularly). The base current only resupplyes holes via relaxation to neutralize the charge imbalance. Due to surface recombination, the base current is relatively small for 45 μm diameter HBTs. As such, the base current is estimated primarily as bulk hole Shockley Reed (HSR) recombination, Auger process, and radiative recombination. To radiation process in the base region of the HBT, the light emission intensity ΔI is proportional to the component of the base current supplying radiative recombination i _Brad, radiative recombination i _Brad excess minority carriers Δn neutral base region, a charge q, It is proportional to the emitter region A _E and inversely proportional to the radiative recombination lifetime τ _rad (Appl. Phys. Lett. 84, 151, Jan. 5, 2004 by M. Feng, N. Holonyak, and W. Hafez).

FIG. 23 (a) shows a top layout of a 45 μm diameter HBT, and FIG. 23 (b) shows a clear guided light from the base layer of the base open space to the emitter region through a microscope equipped with a charge coupled device detector. A diagram of the same HBT with radiation (recombination radiation) is shown. The forward bias was used individually (data not shown) on the emitter-base (EB) junction simply to reveal the light-emitting aperture of the HBT. It is also clear that stimulated light emission is not seen in the base vacant space with respect to the collector region under reverse-bias operation of the collector-base (CB) junction, because any electrons near the HBT collector junction This is because it does not have time to be swept away and recombined with the base holes. In other words, HBT light is observed in the EB base region and not in the CB region. FIG. 24 demonstrates an approximately linear relationship of output light radiation intensity (recombination radiation) as a function of base current. In this example, less than 31% of the light emission from the LET can be collected because the multimode fiber diameter is 25 μm. For a QW base HBT, the common emitter DC current gain beta (β = ΔI _C / ΔI _B ) is β = 13.5 (I _B = 3 mA, I _C = 40.5 mA), and the corresponding common base DC The current gain alpha (α = ΔI _C / ΔI _E ) is approximately 0.93.

The light emission wavelength of an element operating as an HBT (see FIG. 25) is concentrated around 910 nm for GaAs interband recombination transitions and around 960 nm for InGaAs QW transitions. GaAs and (from the gap _{E q)} for both InGaAs QWs transition peak light emission in the longer wavelength direction occurs during the growth of the heavily doped p-type base ^{_{(N A = 4 × 10 19}} cm -3) This is due to the state of the bottom of the donor impurity (N _D > 4 × 10 ¹⁸ cm ⁻³ ). The light emission extends from 825 nm to 910 nm due to hot electron injection from the InGaP emitter into the p-type GaAs base, and subsequent relaxation and recombination results in long wavelength emission.

The pattern generator generated an AC input signal at 1 GHz for the light output modulation test. HBT light combines with a 25 μm core diameter in a multimode fiber probe and captures only a small amount of light. The light is fed into a silicon avalanche photodetector (APD) equipped with a 20 dB linear amplifier. The 3 dB bandwidth of APD with a linear amplifier was 700 MHz. The current gain cutoff frequency f _t was measured at 1.6 GHz for a 45 μm diameter HBT. The power gain cutoff frequency f _max was 500 MHz. FIG. 26 shows traces from a four channel sampling oscilloscope and shows the operation of three ports. The top trace (a) is the input signal (port 1) modulated at 1 GHz with a peak-to-peak amplitude of 0.5 V, and the second trace (b) is biased at I _B = 3 mA. The common emitter HBT and collector-emitter (CE) bias V _CE = 0.17V peak-to-peak output voltage amplitude (Port 2) with V _CE = 2.5V. The third trace (c) shows the optical output signal (port 3) modulated at 1 GHz with a peak-to-peak amplitude of 1 mV. The light output of the LET is modulated faster than the power gain cutoff frequency f _max and, in fact, faster than the current gain cutoff frequency f _t of the HBT, because the base recombination process is a delay in transport time ahead of the HBT Because it is much shorter. This example enhances the quantum well of the HBT-based recombination and establishes the operation of the fast three ports of the quantum well HBT in a common emitter bias structure.

FIG. 27 shows a vertical cavity surface emitting laser according to an embodiment of the invention that employs light emission from the base region of the HBT. A substrate 1105 is provided, and the following other layers are provided thereon: DBR reflective layer 1108, subcollector 1110, collector 1130, transition layer 1133, base 1140, emitter 1150, emitter cap layer 1160 and tip DBR reflective layer 1168. Is done. A collector metallization 1115, a base metallization 1145, and an emitter metallization 1165 are also shown. A collector lead 1117, a base lead 1147, and an emitter lead 1167 are also shown. In the form of this embodiment, the layers are grown by MOCVD, the substrate 1105 is a semi-insulating InP substrate, the subcollector 1110 is n ⁺ InGaAs, the collector 1130 is n InP, and the base 1140 is accompanied by a quantum well. The p ⁺ InGaAs layer, the emitter 1150 is n-type InP, and the emitter cap 1160 is n ⁺ InGaAs. The transition layer is an n-type quadruple transition layer, for example, InGaAsP. In this embodiment, the reflective layers 1108 and 1168 are multi-layer DBR reflective layers spaced by a suitable distance, such as half wavelength. In operation, light emission modulated by modulation of the base current is generated using a signal applied to the three-terminal mode, as is conventional, where vertically emitted laser light is represented by arrow 1190. As mentioned above, it should be understood that other structures and material systems may be used, including, by way of example, GaAs and GaN based HBTs, or other direct bandgap material systems. The base layer 1140 can also be provided with a quantum well or quantum dot layer, as described elsewhere.

FIG. 28 shows a further embodiment of a vertical cavity surface emitting laser that has a Bragg reflector as close as possible to the collector and eliminates the interference of the lower gap absorbing layer between the DBRs. In particular, in FIG. 28 (having reference numbers similar to FIG. 1 for corresponding elements), the lower HBR is indicated by 111 and the upper DBR is indicated by 143. An arrow 190 represents the optical standing wave of the VCSEL. The DBR 141 can be a deposited Si—SiO ₂ Bragg reflector. A further reflector is provided on the emitter 150. Also, the base layer 140 is provided with a quantum well or quantum dot layer as described elsewhere.

  FIG. 29 shows a display 1310 that uses an array 1331, 1332, 1341, etc. of light emitting HBTs. The light output intensity can be controlled as previously described. Very fast operation can be achieved with or without useful light radiation from several elements. Elements and arrays of these elements can be employed in integrated optics and electronics systems.

  In FIG. 30A, the base region 140 of a bipolar transistor (eg, the heterojunction bipolar light emitting transistor of FIG. 1) is relatively close to the first relatively thick quantum well 3041 and the emitter region 150 that are relatively close to the collector region 130. Second relatively thin quantum well 3042. Well-shaped grading is used to facilitate carrier transport from emitter to collector. (For a stepwise energy gap for GaAs wells that alternate with AlAs barriers in laser diodes, see “Quantum-Fell And Least Lattice: Quantum-Fell And Least Lattice by N. Holonyak, 1984 Plenum Press“ The Physics Of Substructure Structures ”1-18. See "Effects"). The quantum well regions 3041 and / or 3042 can alternatively be quantum dot regions, or one can be a quantum well region and the other can be a quantum dot region. Regions 3041 and 3042 can also have different configurations as desired. Also, the spacing between quantum wells (and / or quantum dot regions) differs in thickness and / or configuration. This shape of the invention is further understood from the embodiment shown in FIG. 30B where the base region 140 includes spaced quantum wells 3046, 3047, 3048 and 3049. In the example of this embodiment, the quantum well 3046 closest to the collector is 80 angstroms thick, the next quantum well (3047) is 40 angstroms thick, the next quantum well (3048) is 20 angstroms thick, and (emitter 150) The (closest) quantum well 3049 is 10 angstroms thick. In this example, the spacing or barrier between quantum wells is in the range between approximately 5 angstroms and 50 angstroms, and not necessarily all the same. The injected electrons are trapped in the small well, tunneled in the next large well, and then the next large tunnel, etc., and tunneled and relaxed to the lowermost state of the largest well, with the largest well closest to the collector And recombine. The well arrangement facilitates carrier transport in a certain direction from the emitter to the collector. Maximum recombination and maximum luminous intensity arise from the largest well as close as possible to the collector, which is in an advantageous position for reasons such as optical cavities. Carriers diffuse “down” in energy, ie towards thicker wells. The asymmetric well size improves the direction and speed of carrier transport. In embodiments such as light emitting HBT, both light emission and device speed are improved. As already mentioned, any or all quantum wells can be quantum dot regions and / or made with different configurations other than other quantum well (or dot) regions. It is also understood that many other wells can be used and that some quantum wells (or dot areas in some cases) in the base region can have the same thickness as other quantum wells in the base region. I want to be.

  The principle in this regard also potentially has application to HBT indirect bandgap materials (such as Ge and Si) with a heavily doped base region, and optionally an optical port coupled to the base region. The light produced is typically less intense than the light produced by the direct bandgap HBT light emitter associated therewith. However, this light generation and coupling of Ge-Si systems for a variety of applications involving devices with one or more quantum wells and / or one or more quantum dot regions to enhance recombination It is useful to have the function of

FIG. 2 is a simplified, not full-scale view of an element that can be used in accordance with embodiments of the present invention and in performing method embodiments of the present invention. FIG. 2 is a top view of the layout of the device of FIG. 1 for an embodiment of the present invention. It is the figure seen from the CCD microscope of the test element by embodiment of this invention. FIG. 4 is a simplified schematic diagram of a three port device according to an embodiment of the present invention. FIG. 2 is a graph of common emitter output characteristics of test elements and also shows observed light emission. Oscilloscope traces 6A and 6B are included, showing the input reference optical waveform and the output modulated optical waveform for the test element, respectively. FIG. 6 is a graph showing light output as a function of base current for a test element. FIG. Type II InP / GaAsSb / InP double heterojunction bipolar transistor (DHBT), light emitting transistor (LET) with a 30 nm p-type GaAsSb base that generates a recombination-radiated signal in normal transistor operation (reverse biased collector) ) Diagram and band diagram. FIG. 9 shows common emitter output characteristics of the type II transistor of FIG. 8 (emitter region is 120 × 120 μm ² ), that is, collector current vs. collector-emitter voltage (IV curve). FIG. 9 is a graph of the light emission intensity (recombination emission) of the type II DHBT of FIG. The inset shows the wavelength of recombination radiation from the p-type GaAsSb base at various base currents. Three ports of type II DHBT of FIG. 8 biased with a common emitter structure, (a) 10 kHz input signal (top trace, port 1), (b) amplified output signal (middle trace, port 2), And (c) shows the operation of the optical output modulated at 10 kHz (bottom trace, port 3). 1 illustrates an embodiment of the invention including a light reflector. 1 shows a laser device according to an embodiment of the present invention. Fig. 4 shows a portion of a device according to an embodiment of the invention incorporating one or more quantum wells or quantum dot regions. FIG. 3 is a simplified, non-full scale cross-sectional view of an element that can be used in accordance with embodiments of the present invention and in carrying out method embodiments of the present invention. FIG. 16 is an energy band diagram for the illustration of the device of FIG. 4 is an energy band diagram for an illustration of another device according to an embodiment of the invention. Figure 6 is an energy band diagram for an illustration of a further element according to an embodiment of the invention. FIG. 4 is a diagram of energy bands and energy structures for additional devices with multiple quantum wells, according to embodiments of the invention. FIG. 4 is a diagram of energy bands and energy structures for additional devices with multiple quantum wells, according to embodiments of the invention. FIG. 4 is a diagram of energy bands and energy structures for additional devices with multiple quantum wells, according to embodiments of the invention. Quantum well (QW) InGaP / GaAs heterojunction bipolar transistor (QW HBT), light emitting transistor with two 50Å InGaAs QWs embedded in a p-type GaAs base to facilitate electron capture and enhance recombination radiation (LET) diagram and band diagram. (A) is a CCD upper surface image of the layout of QW InGaP / GaAs HBT of FIG. (B) is a CCD top image of QW HBT light emission of a common emitter structure with current bias (normal transistor operation, I _B = 1 mA). The optical output intensity (power) of the QW HBT of FIG. 22 as a function of base current is shown, demonstrating that it increases approximately linearly with current. DC beta (β = I _c / I _b ) is also shown, and a change from 7 to 13 is seen as the base current increases. The emission wavelength by the base InGaAs quantum wells in the p-type among GaAs-based band recombination and QW HBT of FIG. 22 and FIG. 23 shows a graph of the time is _{I B} 1 mA, a 2mA and 3mA. Operation of the three ports of the QW HBT of FIGS. 22 and 23 biased with a common emitter structure: (a) 1 GHz input signal (top trace, port 1), (b) amplified output signal (middle trace) , Ports 2) and (c) 1 GHz modulated optical output (bottom trace, port 3). 1 is a simplified cross-sectional view of a longitudinal cavity surface emitting laser according to an embodiment of the present invention that is not full-scale. FIG. FIG. 4 is a simplified cross-sectional view of a longitudinal cavity surface emitting laser according to a further embodiment of the present invention, not full scale. FIG. 3 is a simplified diagram of an array according to an embodiment of the invention. FIG. 3 is a cut-away cross-sectional view, not full scale, of an element that can be used in accordance with embodiments of the invention and in carrying out method embodiments of the invention.

Explanation of symbols

105 Substrate 110 Sub-collector 111 Lower HBR
115 Collector Metallization 117 Collector Lead 130 Collector 140 Base 141 Quantum Well 142 Quantum Well 143 Quantum Dot 144 Quantum Dot 145 Base Metallization 147 Base Lead 150 Emitter 160 Cap Layer 165 Emitter Metallization 167 Emitter Lead 190 VCSEL Optical Standing Wave 810 3-terminal optical radiation HBT
820 Reflection cup 910 Three-terminal light emission HBT
920 reflector 1105 substrate 1108 DBR reflective layer 1110 subcollector 1115 collector metallization 1117 collector lead 1130 collector 1133 transition layer 1140 base 1145 base metallization 1147 base lead 1150 emitter 1160 emitter cap layer 1165 emitter metallization 1167 emitter lead 1168 tip DBR reflection Layer 1190 Vertically emitted laser light 1310 Display 1331 Array of light emitting HBTs 1332 Array of light emitting HBTs 1341 Array of light emitting HBTs 3041 Quantum well region 3042 Quantum well region 3046 Quantum well 3048 Quantum well 3049 Quantum well

Claims (93)

In an element having an input port that receives an electrical input signal, an electrical output port that outputs an electrical signal modulated by the input signal, and an optical output port that outputs an optical signal modulated by the input signal,
The device comprises a heterojunction bipolar transistor device comprising a collector, a base and an emitter region;
The input port includes an electrode coupled to the base region, the electrical output port includes an electrode coupled to the collector and emitter regions, and the light output port includes optical coupling to the base region. Element to do.   The device of claim 1, wherein the heterojunction bipolar transistor device comprises a region of direct bandgap semiconductor material. A heterojunction bipolar transistor structure including a collector, base and emitter of direct bandgap semiconductor material;
An optical resonant cavity surrounding at least a portion of the transistor structure;
A semiconductor laser comprising means for coupling an electrical signal and the collector, base and emitter regions to cause laser radiation from the transistor structure.   4. The heterojunction transistor according to claim 3, wherein at least a part of the heterojunction transistor is layered and the optical resonant cavity is a cavity transverse to the layer plane of the at least part of the structure. Laser.   4. The heterojunction transistor structure according to claim 3, characterized in that at least part of the heterojunction transistor structure is layered and the optical resonant cavity is a cavity perpendicular to the layer plane of the at least part of the structure. The laser described.   The laser of claim 3, wherein the heterojunction bipolar transistor structure comprises an InP-based device.   The laser of claim 3, wherein the heterojunction bipolar transistor structure comprises a GaAs-based device.   4. The laser of claim 3, wherein the heterojunction bipolar transistor structure includes a GaN-based device. A heterojunction bipolar transistor structure including a collector, base and emitter of direct bandgap semiconductor material;
At least one quantum well disposed in the base region;
A semiconductor device for generating controllable light emission, comprising means for combining an electrical signal with the collector, base and emitter regions to cause light emission from the device by radiative recombination in the base region .   The device of claim 9, further comprising an optical resonant cavity surrounding at least a portion of the transistor structure.   11. The means of claim 9 or claim 10, wherein the means for combining the electrical signals includes means for applying a collector-emitter voltage and modulating the light output using the applied base current. element. An array of heterojunction bipolar transistor devices including collector, base and emitter regions of direct bandgap semiconductor material; and
A display comprising means for applying an electrical signal across the terminals coupled to the collector, base and emitter regions of the device to cause light emission by radiative recombination in the base region of the device.   13. A display as claimed in claim 12, characterized in that the means for applying a signal comprises modulating the light output of individual elements of the array by applying a signal that controls the base current of the elements. . Providing a heterojunction bipolar transistor device comprising a collector, a base and an emitter region;
In order to cause light emission by radiative recombination in the base region, an electrical signal is applied across the terminals coupled to the collector, base and emitter regions, and optical coupling with light emitted from the base region is achieved. An optoelectronic method comprising the step of providing.   The method of claim 14, wherein applying the electrical signal comprises modulating the light output by applying a collector-emitter voltage and applying a modulation base current.   15. The method of claim 14, wherein providing the heterojunction bipolar transistor device comprises providing a device formed of a direct bandgap material.   The method of claim 14, wherein providing the heterojunction bipolar transistor device comprises providing a device formed of an indirect bandgap material.   15. The method of claim 14, wherein applying an electrical signal to cause the light emission includes applying a base current that generates light emission substantially proportional to the applied base current. 18. The method according to any one of 17.   19. The method of any one of claims 14 to 18, wherein providing the heterojunction bipolar transistor comprises providing at least one quantum well layer in a base region of the heterojunction bipolar transistor. The method described in 1.   20. The method of any one of claims 14 to 19, wherein providing the heterojunction bipolar transistor comprises providing at least one quantum dot region in a base region of the heterojunction bipolar transistor. The method described in 1. Providing a bipolar transistor having an emitter, base and collector region;
Providing an electrode that couples the electrical signal with the emitter, base and collector regions, and adapting the base region to enhance stimulated emission against the disadvantages of spontaneous emission, thereby carrier recombination in the base region A method for increasing the speed of a bipolar transistor, comprising the step of reducing lifetime.   The method of claim 21, wherein adapting the base region comprises providing a layer exhibiting a quantum size effect within the base region.   The method of claim 21, wherein adapting the base region comprises providing a quantum well in the base region.   24. The method of claim 23, wherein providing a quantum well in the base region comprises providing a quantum well having a thickness of about 100 angstroms or less.   The method of claim 21, wherein the step of adapting the base region comprises providing a layer of quantum dots in the base region.   The method of claim 21, wherein adapting the base region comprises providing a plurality of quantum wells in the base region.   27. The method of claim 26, wherein providing a plurality of quantum wells in the base region includes providing a plurality of quantum wells having a thickness of approximately 100 angstroms or less.   25. Providing a quantum well in the base region comprises providing a quantum well of a material having a narrower band gap than the band gap of the base region material. The method described in 1.   The method of claim 21, wherein adapting the base region comprises placing the base region in an optical cavity.   24. A method according to claim 22 or claim 23, wherein the step of adapting the base region comprises disposing the base region in an optical cavity.   The emitter, base, and collector regions are provided in a vertical layer structure, and the step of adapting the base region further includes disposing the base region in a lateral optical cavity, The method of claim 21.   The emitter, base, and collector regions are provided in a vertical layer structure, and adapting the base region includes disposing the base region in a vertical optical cavity. Item 23. The method according to Item 22.   The method of claim 21, wherein adapting the base region includes placing the base region in an optical cavity that includes a reflector through which optical radiation is partially transmitted.   The method of claim 21, wherein adapting the base region includes placing the base region in a fully reflective optical cavity. Providing an indirect bandgap semiconductor material heterojunction bipolar transistor having a heavily doped base region between an emitter region and a collector region;
Providing an electrode for coupling the electrical signal with the emitter, base and collector regions, and adapting the base region to enhance stimulated radiation against the disadvantages of spontaneous radiation, thereby carrier recombination of the base region A method for increasing the speed of said heterojunction bipolar transistor, comprising the step of reducing lifetime.   36. The method of claim 35, wherein adapting the base region comprises providing a layer exhibiting a quantum size effect in the base region.   36. The method of claim 35, wherein adapting the base region comprises providing a quantum well in the base region.   38. The method of claim 37, wherein providing a quantum well in the base region comprises providing a quantum well having a thickness of approximately 100 angstroms or less.   36. The method of claim 35, wherein adapting the base region comprises providing a quantum dot layer in the base region.   36. The method of claim 35, wherein adapting the base region comprises providing a plurality of quantum wells in the base region.   41. The method of claim 40, wherein providing a plurality of quantum wells in the base region comprises providing a plurality of quantum wells having a thickness of approximately 100 angstroms or less.   39. The step of providing a quantum well in the base region includes providing a quantum well of a material having a narrower band gap than that of the material of the base region. The method described in 1.   36. The method of claim 35, wherein adapting the base region comprises disposing the base region in an optical cavity.   38. A method according to claim 36 or claim 37, wherein adapting the base region further comprises placing the base region in an optical cavity.   The emitter, base, and collector regions are provided in a vertical layer structure, and adapting the base region includes disposing the base region in a lateral optical cavity. Item 36. The method according to Item 35.   The emitter, base, and collector regions are provided in a vertical layer structure, and adapting the base region includes disposing the base region in a vertical optical cavity. Item 36. The method according to Item 35.   36. The method of claim 35, wherein adapting the base region includes placing the base region in an optical cavity that includes a reflector through which optical radiation is partially transmitted.   37. The method of claim 36, wherein adapting the base region comprises placing the base region in a fully reflective optical cavity.   38. The method of claim 37, wherein providing the heterojunction bipolar transistor includes providing the InP transistor with an undoped InGaAs quantum well in a heavily doped p-type InP base region. Method.   38. The method of claim 37, wherein providing the heterojunction bipolar transistor comprises providing the InP transistor with an undoped InGaAs quantum well in a heavily doped p-type InGaAsP base region. Method.   38. The method of claim 37, wherein providing the heterojunction bipolar transistor comprises providing an InP transistor with an undoped GaAsSb quantum well in a heavily doped p-type InP base region. Method.   38. The method of claim 37, wherein providing the heterojunction bipolar transistor comprises providing an InP transistor with an undoped InGaAs quantum well in a heavily doped p-type GaAsSb base region. Method.   38. The method of claim 37, wherein providing the heterojunction bipolar transistor comprises providing the GaAs transistor with an undoped InGaAs quantum well in a heavily doped p-type GaAs base region. Method. A heterojunction bipolar transistor having a collector, base, and emitter region;
At least one quantum well in the base region;
A semiconductor device comprising means for coupling an electrical signal to the collector, base, and emitter regions.   55. The device of claim 54, wherein the at least one quantum well has a thickness of about 100 angstroms or less.   55. The device of claim 54, wherein the at least one quantum well in the base region includes a plurality of spaced apart quantum wells in the base region.   57. The device of claim 56, wherein each of the plurality of quantum wells has a thickness of about 100 angstroms or less.   55. The device of claim 54, further comprising an optical cavity around the base region. A heterojunction bipolar transistor having a collector, base, and emitter region;
Means for coupling the electrical signal with the collector, base, and emitter regions;
A semiconductor device comprising an optical cavity around the base region. A heterojunction bipolar transistor of indirect bandgap semiconductor material having a heavily doped base region between the collector region and the emitter region;
Means for coupling the electrical signal with the collector, base, and emitter regions;
A semiconductor device comprising means for adapting the base region to enhance stimulated radiation against the disadvantages of natural radiation, thereby reducing the carrier recombination lifetime of the base region. A bipolar transistor having a base region between the collector region and the emitter region;
Means for coupling the electrical signal with the collector, base, and emitter regions;
A semiconductor device comprising a plurality of quantum size regions spaced apart from each other in the base region, wherein at least some of the plurality of quantum size regions have different thicknesses.   62. The device of claim 61, wherein the quantum size region is a quantum well.   62. The device of claim 61, wherein the quantum size region is a quantum dot region.   62. The device of claim 61, wherein at least one of the quantum size regions is a quantum well, and at least one of the quantum size regions is a quantum dot region.   62. The device of claim 61, wherein the bipolar transistor is a heterojunction bipolar transistor.   62. The device of claim 61, wherein the at least some of the plurality of quantum size regions having different thicknesses differ in thickness every at least 10 angstroms.   64. The device of claim 62, wherein the at least some of the plurality of quantum wells having different thicknesses differ in thickness every at least 10 angstroms.   The plurality of quantum size regions includes a first quantum size region relatively close to the collector region and a second quantum size region relatively close to the emitter region, and the first quantum size region is the 62. The method of claim 61, wherein the method is thicker than the second quantum size region.   The plurality of quantum wells includes a first quantum well relatively close to the collector region and a second quantum well relatively close to the emitter region, and the first quantum well is the second quantum well. 64. The method of claim 62, wherein the method is thicker than the well.   69. The device of claim 68, wherein the first quantum size region is at least 10 angstroms thicker than the second quantum size region.   69. The device of claim 68, wherein the first quantum well is at least 10 angstroms thicker than the second quantum well.   72. The device of claim 70 or 71, wherein the base region is a p-type semiconductor.   71. The base of claim 70, wherein the base region is a heavily doped p-type indirect bandgap semiconductor and the quantum size region is made of a wider bandgap material than the material of the base region. element.   72. The device of claim 71, wherein the base region is a heavily doped p-type indirect bandgap semiconductor and the quantum well is made of a wider bandgap material than the material of the base region.   74. The device of claim 73, wherein the quantum size region is substantially undoped.   75. The device of claim 74, wherein the quantum well is substantially undoped. Providing a bipolar transistor having an emitter, base, and collector region;
Providing an electrode for coupling an electrical signal to the emitter, base, and collector regions; and a second quantum region relatively close to the emitter region and a first quantum size region relatively close to the collector region. Adapting the base region to facilitate carrier transport from the emitter region to the collector region by providing a quantum size region, and wherein the first quantum size region is the second quantum size A method for improving the operation of a bipolar light emitting transistor, characterized in that it is thicker than the region.   78. The method of claim 77, wherein providing the quantum size region comprises providing a quantum well.   78. The method of claim 77, wherein providing the quantum size region comprises providing a quantum dot region.   78. The method of claim 77, wherein providing the quantum size region comprises providing a quantum well and a quantum dot region.   78. The method of claim 77, wherein providing the bipolar light emitting transistor comprises providing a heterojunction bipolar light emitting transistor. Providing a bipolar light emitting transistor having an emitter, base, and collector region;
Providing an electrode that couples an electrical signal with the emitter, base, and collector regions; and providing the base region with a plurality of spaced quantum size regions of different thicknesses from the emitter region to the collector region Adapting the base region to facilitate carrier transport to, and wherein the thickness of the quantum size region is rated from the thickest near the collector to the thinnest near the emitter A method for improving the operation of a bipolar light emitting transistor.   84. The method of claim 82, wherein providing the quantum size region comprises providing a quantum well.   The method of claim 82, wherein providing the quantum size region comprises providing a quantum dot region.   83. The method of claim 82, wherein providing the quantum size region comprises providing at least one quantum well and at least one quantum dot region.   83. The method of claim 82, wherein providing the bipolar light emitting transistor comprises providing a heterojunction bipolar light emitting transistor. A heterojunction bipolar transistor having a base region between the collector region and the emitter region;
Means for coupling the electrical signal with the collector, base, and emitter regions;
A semiconductor light emitting device comprising a plurality of spaced quantum size regions of the base region, wherein at least some of the plurality of quantum size regions have different thicknesses.   88. The device of claim 87, wherein the quantum size region is a quantum well.   88. The device of claim 87, wherein the quantum size region is a quantum dot region.   88. The device of claim 87, wherein at least one of the quantum size regions is a quantum well, and at least one of the quantum size regions is a quantum dot region.   88. The device of claim 87, wherein the at least some of the plurality of quantum size regions having the different thicknesses differ in thickness every at least 10 angstroms.   The plurality of quantum size regions includes a first quantum size region relatively close to the collector region and a second quantum size region relatively close to the emitter region, and the first quantum size region is the 88. The method of claim 87, wherein the method is thicker than the second quantum size region.   93. The device of claim 92, wherein the first quantum size region is at least 10 angstroms thicker than the second quantum size region.

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