CN1309094C

CN1309094C - Hole resonance tunnel-through diode based on Si/SiGe

Info

Publication number: CN1309094C
Application number: CNB2004100062432A
Authority: CN
Inventors: 陈培毅; 熊晨荣; 邓宁; 王燕; 王民生
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2004-03-17
Filing date: 2004-03-17
Publication date: 2007-04-04
Anticipated expiration: 2024-03-17
Also published as: CN1564325A

Abstract

The present invention discloses a cavity type resonant tunneling diode based on Si/SiGe, which belongs to the technical field of a novel semiconductor device and a nanoelectronic device. A straining SiGe layer is used as a cavity quantum well, and Si is used as a cavity potential barrier. Thus, a cavity double potential barrier single quantum well structure is formed. High mixing P-shaped Si is used as a substrate. An unmixed SiGe layer, a Si layer, a SiGe layer, a Si layer, a SiGe layer and a heavily-mixed P-shaped Si layer are successively deposited on the substrate in a chemical gas-phase deposition method or a molecular beam epitaxy method, etc., which forms a mesa structure. Electrodes are respectively formed on the substrate and the mesa structure. By experiment, under room temperature, current and voltage characteristics of a sample are tested, which can observe an obvious differential negative resistance phenomenon. A fabrication process of the present invention is compatible to the existing mainstream Si semiconductor planar process, which can efficiently increase the integration level of an integrated circuit.

Description

Cavity type resonance tunnel-through diode based on Si/SiGe

Technical field

The invention belongs to novel semi-conductor device and nano electron device field, particularly a kind of cavity type resonance tunnel-through diode based on Si/SiGe.

Background technology

Along with the continuous development of silica-based very lagre scale integrated circuit (VLSIC) planar technique technology, the characteristic size of microelectronic component is constantly dwindled day by day near its physics limit.On this size magnitude, the quantum effect of microelectronic component will be occupied an leading position in carrier transport and device work.This characteristic size is that nanometer scale and the semiconductor device that utilizes quantum effect work are commonly referred to as the nanometer quantum device.For example: quantum dot device, single-electron device, resonance tunnel-through diode or the like.Wherein, resonance tunnel-through diode is comparatively ripe and have unique differential negative resistance characteristic because of its fabrication and processing technology, is subjected to numerous researchers' favor more.It is used for circuit design such as high-frequency generator, MULTI-VALUED LOGIC CIRCUIT and memory circuitry and can reduces device cell number in the circuit effectively, and can reduce chip area.So resonance tunnel-through diode is acknowledged as one of nanometer quantum device that is rich in development prospect.

U.S. Pat 6229153 has been announced a kind of method of the GaAs/AlGaAs/InGaAs of employing material preparation resonance tunnel-through diode.But this kind method exists the cost height, with problem such as the Si semiconductor planar technology of current main-stream is incompatible, makes its application be subjected to great restriction.

The present invention proposes a kind of cavity type resonance tunnel-through diode based on Si/SiGe.The Si semiconductor planar technology of its manufacture craft and current main-stream is compatible mutually, integrated level that can more effective raising integrated circuit.Adopt the principle of Si/SiGe material cavity type resonance tunnel-through diode as follows: when the thickness of epitaxially grown SiGe strained layer on the Si substrate during less than its critical thickness, can be with the discontinuous valence band that mainly appears at, conduction band approximate continuous between relaxation Si and the strain SiGe.We utilize the required double potential barrier single quantum of discontinuity structure cavity type resonance tunnel-through diode of this valence band just.

Summary of the invention

The objective of the invention is to propose a kind of cavity type resonance tunnel-through diode based on Si/SiGe.It is characterized in that adopting the strain SiGe layer to do the hole quantum well, unadulterated Si does the hole potential barrier.Its chief component has: highly doped P type Si substrate, adopting chemical gas-phase deposition method or the molecular beam epitaxial method mesa structure that unadulterated SiGe layer, Si layer, SiGe layer, Si layer, SiGe layer and heavily doped P type Si form in the deposit successively on this substrate and respectively on the substrate and the electrode that splash-proofing sputtering metal forms on the mesa structure.The invention has the beneficial effects as follows to have to experimental results show that it has reached intended purposes, at room temperature can observe tangible differential negative resistance phenomenon.The Si semiconductor planar technology of manufacture craft and current main-stream is compatible mutually, integrated level that can more effective raising integrated circuit.

Description of drawings

Fig. 1 a. is the cavity type resonance tunnel-through diode structural representation based on Si/SiGe.

Fig. 1 b is the corresponding energy band diagram of Fig. 1 a..

Fig. 2 a. bias voltage is a valence-band level schematic diagram under the O.

Fig. 2 b bias voltage is a valence-band level schematic diagram under the Va.

Fig. 2 C bias voltage is a valence-band level schematic diagram under the Vb.

Fig. 2 d. is the current-voltage correlation curve synoptic diagram based on the cavity type resonance tunnel-through diode of Si/SiGe.

Fig. 3 is the current-voltage correlation curve chart based on the cavity type resonance tunnel-through diode of Si/SiGe of test.

Embodiment

Fig. 1 a is depicted as the cavity type resonance tunnel-through diode structural representation based on Si/SiGe.Adopt the double potential barrier single quantum, (doping content requires greater than 1E+19cm in heavy doping P type ^-3) on the Si substrate 7, adopt CVD (Chemical Vapor Deposition) method following each layer of growing successively: thickness is the SiGe layer 1 of 8nm-20nm, and wherein Ge accounts for volume ratio 0.2-0.5%, as a spacer district; Thickness is the Si layer 2 of 1nm-6nm, as first barrier region; Thickness is the SiGe layer 3 of 2nm-6nm, and wherein Ge accounts for volume ratio 0.2-0.5%, as quantum well region; Thickness is the Si layer 4 of 2nm-6nm, as second barrier region; Thickness is the SiGe layer 5 of 8nm-20nm, and wherein Ge accounts for volume ratio 0.2-0.5%, as the 2nd spacer district; Thickness is that (doping content is greater than 1E+19cm for the heavy doping P type of 1um-3um ^-3) Si layer 6 does contact layer, in order to make contact conductor.

The energy band diagram of structure correspondence is shown in Fig. 1 b shown in Fig. 1 a.When the thickness of epitaxially grown SiGe strained layer on the Si substrate during, can be with the discontinuous valence band that mainly appears at, conduction band approximate continuous between relaxation Si and the strain SiGe less than its critical thickness.And body Si forbidden band is wideer than the forbidden band of strain SiGe, so the Si layer is done

hole barrier layer

2 and 4; The strain SiGe layer is done hole quantum well region 3 (shown in Fig. 1 b).Because the SiGe layer as quantum well region 3 is very thin, near the magnitude of the de Broglie wavelength of electronics, the hole energy level in the trap splits into several discrete energy levelss according to quantum effect.In Fig. 2 a, provided the situation of thermal equilibrium state when bias voltage is zero.When bias voltage increased, the place of the nearly potential barrier of anode one side joint formed a hole accumulation region, at the place formation depletion region of negative electrode one side near potential barrier.Have only hole seldom tunnelling to pass through double potential barrier.In case when bias voltage reaches the Va value, the energy state that is occupied in the anode one side valence band is flushed with the empty energy state of E1 in the quantum well, resonance tunnel-through takes place in this moment, shown in Fig. 1 b, Fig. 2 b.In this point, many holes can tunnelling enter in the quantum well region 3 by left side barrier layer 2, and then tunnelling enters the energy state that is not occupied in the negative electrode one side valence band by the right barrier layer 4.When bias voltage further was increased to Vb, the valence-band edge on the left side rose and to exceed E1 among Fig. 2 a, and the electron number of can tunnelling crossing potential barrier reduces sharply, shown in Fig. 2 c.Valley point current mainly is the electric current component that comes from excess carrier, and it increases with the increase of bias voltage.Phonon is assisted or impurity assists tunnelling that this electric current is also had contribution.Based on the cavity type resonance tunnel-through diode current-voltage correlation curve synoptic diagram of Si/SiGe shown in Fig. 2 d.

Should be based on the cavity type resonance tunnel-through diode preparation process of Si/SiGe:

1. each layer film of vapor deposition on off-the-shelf heavy doping P type substrate 7;

2. adopt the good material of RIE dry etching extension, obtain mesa structure;

3. with LPCVD growth one deck SiO ₂As insulating barrier 8;

4. wet etching goes out the electrode contact hole after the photoetching;

5. sputtered aluminum film is as contact conductor;

6. photoetching, erode away underlayer electrode 9 and table top electrode 10, and alloying.

If we add voltage between table top electrode 10 and underlayer electrode 9, the electric current of this unit is flow through in test, and we just can obtain the current-voltage correlation curve of this unit.This based on the cavity type resonance tunnel-through diode sample current voltage curve of Si/SiGe as shown in Figure 3, its curve shape is similar to current-voltage correlation curve shown in Fig. 2 d.

Claims

1. cavity type resonance tunnel-through diode based on Si/SiGe, it is characterized in that: do the hole quantum well with the strain SiGe layer, do the hole potential barrier with Si, form the double potential barrier single quantum in hole, make substrate with highly doped P type Si, the mesa structure that unadulterated SiGe layer, Si layer, SiGe layer, Si layer, SiGe layer and heavily doped P type Si form on methods such as employing chemical gas-phase deposition method or molecular beam epitaxy on this substrate deposit successively, and on substrate, form electrode respectively with the mesa structure splash-proofing sputtering metal.