CN113013260B - Photosensitive SiC heterogeneous junction multi-potential-barrier varactor - Google Patents
Photosensitive SiC heterogeneous junction multi-potential-barrier varactor Download PDFInfo
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. 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
- H01L29/92—Capacitors with potential-jump barrier or surface barrier
- H01L29/93—Variable capacitance diodes, e.g. varactors
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. 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
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- H01L29/66083—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
- H01L29/66181—Conductor-insulator-semiconductor capacitors, e.g. trench capacitors
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Abstract
The invention discloses a photosensitive SiC heterojunction multi-barrier varactor which comprises N arranged in sequence + Type 3C-SiC substrate, at least one set of heterogeneous junctions, N + A type 3C-SiC contact layer; the heterogeneous junction is composed of an N-type 3C-SiC modulation layer, an intrinsic 4H-SiC or 6H-SiC barrier layer and an N-type 3C-SiC modulation layer, wherein in the heterogeneous junction, the N-type 3C-SiC with a narrow band gap is a potential well, and the intrinsic 4H-SiC or intrinsic 6H-SiC with a wide band gap is a potential barrier; a silicon dioxide protective layer is generated on the surface of the isomeric structure, and a shading layer is coated outside the silicon dioxide protective layer; said N is + Type 3C-SiC substrate, N + Ohmic electrodes are respectively arranged on the outer surfaces of the type 3C-SiC contact layers; n is a radical of + And the outer surface of the type 3C-SiC contact layer is provided with a light hole. The invention has the advantages of small leakage current, small capacitance, high cut-off frequency, wide dynamic load modulation range and capacity change by illumination; it is suitable for frequency doubling, parameter amplification, light detection, etc.
Description
Technical Field
The invention belongs to the technical field of electronics, and particularly relates to a semiconductor solid-state high-frequency device, in particular to a photosensitive SiC heterojunction multi-barrier varactor.
Background
Compared with other semiconductor materials, SiC has the same requirements on reverse breakdown voltage because of high critical breakdown field strength, and the material doping in the device prepared from SiC can be higher, so that the inherent internal resistance of the SiC device is small; SiC has high thermal conductivity and saturated electron mobility, and is suitable forFor high temperature, high frequency devices; band gap E of 3C-SiC g 2.39eV, which is equivalent to the photon energy of green light, and can absorb green light; the band gaps of the 4H-SiC and the 6H-SiC are respectively E g ＝3.26eV、E g It absorbs violet light at 3.02 eV. Cubic phase 3C-SiC, hexagonal phase 4H-SiC and hexagonal phase 6H-SiC form 3C/4H-SiC and 3C/6H-SiC isomeric junction barriers with the same components and different structures on two sides of the interface respectively. The heterogeneous junction barrier varactor is structurally and principally different from pn junction varactors, schottky junction varactors, metal/semiconductor/metal (MSM) junction varactors, and metal plate varactors. It can be expected that the 3C/4H-SiC and 3C/6H-SiC heterogeneous junction barrier varactor has the advantages of high temperature, high frequency and high power and is sensitive to green light and near ultraviolet light. The varactor has higher conversion efficiency than a varistor.
Through retrieval, there are technical documents reflecting varactor diodes, mainly:
document 1[ Status and promoters of high-power head-structure barrier reactors, Proceedings of the IEEE, Vol.105, No.6(2017): 1008-; compared with a quantum cascade laser, the heterojunction barrier varactor can work at normal temperature, has higher power, efficiency and adjustability, and has narrower line width of signals; compared with schottky barrier varactors and Gunn (Gunn) diodes, heterojunction barrier varactors have higher power and efficiency because the withstand voltage can be improved and the leakage current can be reduced by increasing the barrier; the maximum output power is limited by the heterojunction barrier height, maximum current density, highest junction temperature and circuit impedance. This review article does not have information about photosensitive SiC heterojunction barrier varactors therein.
Document 2[ Efficient topic-structured distributed-barrier variables diodes, Journal of Applied Physics, Vol.105, No.2(2009):024502-1-5.]In was studied 0.53 Ga 0.47 The capacitance modulation ratio (the ratio of the maximum capacitance to the minimum capacitance C) of the As/AlAs and InN/GaN homojunction barrier donor type doping to the varactor max /C min ) Third harmonic wave (A) 3 /A 1 ) The influence of multiplication efficiency, the shielding length of the potential well layer is not limited when the potential barrier doping is higher than a certain degree, and impurities are ionized to form free charges, so that the C of the varactor is caused max Increase in value, C min The value is not influenced by potential barrier doping, so that the capacitance modulation ratio is increased; third harmonic to fundamental amplitude ratio (A) 3 /A 1 ) The doping rate is increased from 45% when the barrier is not doped to 65% when the barrier is doped.
Document 3[ Balanced MSM-2DEG varactors based on AlGaN _ GaN heter-structure with cutoff frequency of 1.54THz, IEEE Electron devices Letters, Vo.38, No.1(2017): 107-.]Develop Al 0.24 Ga 0.76 An N/GaN heterojunction metal/semiconductor/metal-two-dimensional electron gas (MSM-2DEG) type variable capacitance diode utilizes the Metal Organic Chemical Vapor Deposition (MOCVD) technology to grow an AlN nucleating layer, a Fe-doped GaN transition layer with the thickness of 1.8 mu m and an Al transition layer with the thickness of 22nm on a SiC substrate from bottom to top in sequence 0.24 Ga 0.76 An N Schottky barrier layer and a 3nm thick GaN contact layer; manufacturing structural electrodes of symmetrical grids (2T-shaped grids), asymmetrical grids (1T-shaped grid +1 rectangular grid) and balanced grids (1T-shaped grid +1 rectangular grid on the left and right sides); compared with the resistance and capacitance of the symmetrical gate, asymmetrical gate and balanced gate structures, the contact resistance is reduced due to large contact area in the latter 2, the channel resistance of 2DEG is also reduced due to the balanced gate structure, and the high-frequency resistance is reduced but the edge capacitance is increased due to the T-shaped gate in the latter 2 (maximum capacitance C) max ) (ii) a Cut-off frequency (f) of varactor diode T ) Increased to 1.54THz, capacitance modulation ratio (ratio of maximum to minimum capacitance C) max /C min ) To 2.64, the quality Factor (FOM) reached 4.06 THz.
Document 4[ High-performance 450-GHz GaAs-based heterojunction-structure barrier vector tripler, IEEE Electron Device Letters, Vo.24, No.3(2003): 138-.]Develop Al 0.7 Ga 0.3 An As/GaAs Heterojunction Barrier Varactor (HBV) is prepared by growing GaAs transition layer and Al layer sequentially on semi-insulating GaAs substrate from bottom to top by Molecular Beam Epitaxy (MBE) technique 0.7 Ga 0.3 As etch stop layer, n + N-type GaAs modulation doping with thickness of 250nm and ohmic contact layer of GaAsImpurity layer/3.5 nm thick undoped GaAs spacer layer/Al 0.7 Ga 0.3 An As barrier layer/a 3.5nm thick undoped GaAs spacing layer/a 500nm thick n-type GaAs modulation doping layer, wherein the modulation doping layer/the spacing layer/the barrier layer/the spacing layer/the modulation doping layer-heterojunction has 4 periods; a planar transmission line waveguide (150GHz band stop +450GHz band pass) is manufactured on the dielectric film, an air bridge is not needed, and the parasitic loss is reduced by utilizing a chip flip-chip technology; the measurement shows that the maximum power is 1.05mW, the efficiency is 1.3 percent and the maximum swing efficiency is 1.45 percent at the frequency of 451.8 GHz.
Document 5[ SiC varactors for dynamic load modulation of high power amplifiers, IEEE Electron Device Letters, Vol.29, No.7(2008): 728-.]On the basis of analyzing the C-V relationship, a Hot Wall Chemical Vapor Deposition (HWCVD) technology is utilized to carry out the reaction on N + Growing a layer of nitrogen doped Yi (1+ ax) on the SiC substrate -3 A SiC epitaxial film with regular change and vapor plating on the SiC film
And a Schottky contact electrode for forming a SiC homojunction Schottky barrier varactor. According to (1+ ax) -3 The linearity and the tuning range of the C-V relation can be increased by regular gradient doping, and the modulation ratio exceeds 10; the high critical breakdown field of SiC can increase the doping level under the same voltage requirement, resulting in low loss and high quality factor. Through the anode self-alignment process, the phenomenon that the breakdown voltage is increased due to the fact that the electric field concentration at the edge of the anode is avoided, and the cost that the loss is increased due to the fact that doping is reduced in order to increase the breakdown voltage is not needed to be paid. This article of research does not address the description of photosensitive SiC heterojunction barrier varactors.
Document 6[ Some runs for the choice of the C (V) characteristics for the design of frequency triplers with systematic variables, 2002IEEE MTT-S International Microwave Symposium Digest, Vol.1, No.1(2002): 359-. This document does not relate to photosensitive SiC heterojunction barrier varactors.
Document 7[ heterogeneous-barrier catalysts with non-nuclear modulated layers, Technical Physics Letters, vol.45, No.10(2019):1063-1066 ] designs an InAlAs/AlAs/InAlAs heterojunction barrier varactor with a capacitance-voltage relationship having a symmetric cosine and a current-voltage relationship having an odd symmetric characteristic by using a quantum drift-diffusion model in which a charge density gradient is recorded, and prepares the device on an InP substrate by using a Molecular Beam Epitaxy (MBE) technique. The result shows that the influence of doping mutation in the MBE process is eliminated, and the tested capacitance-voltage and current-voltage relations are consistent with the design condition; the model is suitable for designing the heterojunction barrier variable capacitance diode with any component and any doping. This article does not address the photosensitive SiC heterojunction barrier varactor and the two-dimensional electron (hole) gas at the SiC heterojunction interface.
Document 8[ MSM varactor diodes based on In 0.7 Ga 0.3 As HEMTs with cutoff frequency of 908GHz,IEEE Electron Device Letters,Vol.35,No.2(2014):172-174.]InP/In with variable gate length and gate-trench distance is developed by utilizing Pt-buried gate technology 0.52 Al 0.48 As/In 0.7 Ga 0.3 As/In 0.53 Ga 0.47 MSM-2DEG varactor of As heterojunction HEMT structure. The capacitance switching ratio of the device depends on both the electrode structure and the vertical layer structure, and the design freedom of the device is more than that of an SB (saturation plate) variable capacitance diode. The FOM value of the device can be obviously improved by reducing the gate-channel distance, the cut-off frequency can be improved by compressing the gate length while the same FOM level is kept, and the switch capacitance ratio and the FOM value of the device are increased after annealing. This document is not associated with photosensitive SiC heterojunction barrier varactors.
Document 9[ inorganic capacitors enhanced triggered by light, IEEE Journal of Selected Topics in Quantum Electronics, Vol.21, No.4(2015):3800605-1-5.]Designs of metal/semiconductor (GaAs/Al) introducing two-dimensional hole gas (2DHG) 0.24 Ga 0.76 As/Al 0.9 Ga 0.1 As (15 period superlattice)/GaAs)/metal (MSM) structure varactor type photodetectors compromise the relationship between the speed of the cooperative light response and the quantum efficiency to optimize the thickness of the light absorbing layer. In measuring electricityAnd in the capacitance-voltage relation, the incident light intensity is changed to control the concentration of the 2DHG in the superlattice, so that the capacitance of the varactor is adjusted. The result shows that the capacitance enhancement at the critical voltage reaches 200% when the illumination is enough, the ratio of the peak-to-valley capacitance is more than 4 when the excitation signal frequency is higher than 10kHz, and the ratio of the illumination capacitance to the dark capacitance exceeds 40. The analysis reason is that the concentration of the photo-generated 2DHG in the superlattice changes when the varactor diode is reversely biased, exchange correlation energy is generated, the capacitance of a two-dimensional charge system changes along with the change of the capacitance, and the quantum effect is achieved. The varactor can be used in photoelectric capacitors, phototransistors, photodetectors, photocouplers, etc. In the MOS (metal/oxide/semiconductor) type capacitance-variable diode, a metal plate of a mechanical tuning capacitor is replaced by a material such as a semiconductor, and the reliability is higher by using a voltage-regulated capacitor. This research article is not relevant for photosensitive SiC heterojunction barrier varactors.
Reference 10[ Photo-capacitive light sensor based metal-YMnO3-insulator-semiconductor structures, Applied Physics Letters, Vol.108, No.5(2016):052103-1-5.]Sequential growth of SiN on P-type Si by Pulsed Laser Deposition (PLD) technique x 、YMnO 3 And (3) preparing a film into a metal (Al electrode)/ferroelectric layer/insulator/semiconductor MFIS type light-operated variable capacitance diode. Wherein YMnO 3 Ferroelectric polarization of the layer is aligned to SiN when the diode is forward biased x The insulating layer can increase the minority carrier concentration of the inversion layer at the interface of the insulating layer/semiconductor, and enhance the photo capacitance effect. The result shows that the increment of the capacitance can reflect the change of illumination intensity and wavelength (blue, green, red, near infrared and the like), and is suitable for a light detector and the like. This document does not relate to photosensitive SiC heterojunction barrier varactors and SiC heterojunction interface two-dimensional electron (hole) gas.
Document 11[ Comparison of the efficiency of the epitaxial semiconductor diode of the THz-frequency range, Semiconductors, Vol.54, No.10(2020): 1360-. This document is not associated with photosensitive SiC heterojunctions and SiC heterojunctions interface two-dimensional electron (hole) gas (2DEG or 2 DHG).
Document 12[ InGaAs/InAlAs/AlAs heterojunction-structure resistors on silicon substrate, IEEE Electron devices Letters, vol.32, No.2(2011): 140-; compared with a heterojunction barrier varactor formed by directly epitaxially growing InGaAs/InAlAs/AlAs on an InP wafer, the heterojunction barrier varactor has almost the same capacitance-voltage relationship in unit area, has a symmetrical capacitance-voltage curve relative to 0 voltage and is not influenced by a substrate, and has a symmetrical current density-voltage curve relative to 0 voltage. This paper is independent of the photosensitive SiC heterojunctions and the two-dimensional electron (hole) gas.
Document 13[ InGaN/GaN Schottky diodes with enhanced voltage handling capabilities for vacuum applications, IEEE Electron devices Letters, Vol.31, No.10(2010): 1119-.]In is grown on N-type epitaxial GaN wafer by Metal Organic Chemical Vapor Deposition (MOCVD) 0.4 Ga 0.6 N、In 0.1 Ga 0.9 The N surface layer forms an InGaN/GaN heterojunction Schottky Barrier (SB) varactor, and compared with a Schottky barrier varactor without the InGaN surface layer, the breakdown voltage of the InGaN/GaN heterojunction Schottky Barrier (SB) varactor is improved, and the leakage current is reduced; the breakdown voltage increase is due to a decrease in surface electric field; because of the interface polarization induced charge, the tunneling distance is extended resulting in a reduction in leakage current. However, the capacitance switching ratio of SB varactors relies on a vertical layer structure alone, with less freedom in device design. This document does not relate to photoactive SiC heterojunctions and two-dimensional electron (hole) gas.
Document 14[ ASiC vacuum with large effective tuning range for microwave power applications, IEEE Electron Device Letters, Vol.32, No.6(2011): 788-.]By using Hot Wall Chemical Vapor Deposition (HWCVD) technique on N + Firstly growing a hydrogen doped SiC spacing layer on a type SiC substrate, and then continuously growing nitrogen doping gradient reduction(x -3 ) And depositing a SiC film on the SiC film
The Schottky contact electrode forms a SiC homojunction Schottky barrier variable capacitance diode, and compared with a flat Schottky barrier variable capacitance diode without an interlayer and a gradient doped SiC film, the Schottky barrier variable capacitance diode has the advantages of reduced leakage current, low loss, improved breakdown voltage, high variable capacitance ratio, high quality factor, large signal amplitude modulation range, wide dynamic load modulation range and higher peak-to-average energy efficiency ratio of a parameter amplifier. This paper is independent of the photosensitive SiC heterojunction and the two-dimensional electron (hole) gas.
Document 15[ Design and large-signal characteristics of high-Power variable-based impedance tuners, IEEE transformations on Microwave Theory and Techniques, vol.66, No.4(2018): 1744-. This paper is only a homojunction SiC varactor, independent of the photosensitive SiC heterojunction varactor and the two-dimensional electron (hole) gas.
Document 16[ an exponentially doped GaAs schottky varactor and method of making the same, application No. 201010132087X.]Disclosed is an exponentially doped GaAs Schottky varactor, comprising: semiconductor insulating GaAs substrate, heavily doped N epitaxially grown on the substrate + Layer of N + An N-type GaAs layer epitaxially grown on the N-type GaAs layer and having an exponentially distributed doping concentration, an upper electrode having a Schottky contact evaporated on the N-type GaAs layer, and an N-type GaAs layer formed on the N-type GaAs layer + A lower electrode in ohmic contact with the layer formed by evaporating metal; a manufacturing method of the variable capacitance diode is also disclosed. Can improve the capacitance ratio and enhance the nonlinearity by adjusting the doping concentration of the N-type GaAs layer on the premise of not changing the structure of the traditional Schottky diode, can be used in a periodic nonlinear transmission line, and can improve millimeter waves and submillimeter wavesThe working frequency and the output power of the frequency doubling circuit in the range. This document does not relate to photosensitive SiC heterojunction varactors and two-dimensional electron (hole) gas.
Document 17[ gaussian doped gallium arsenide schottky varactor and method of making same, application No. 2009103123924.]A Gauss doped GaAs Schottky variable capacitance diode is composed of a semiconductor insulating GaAs substrate, a high-doped N layer on the substrate + Type layer of N + N type layer on top of the type layer, in N + An ohmic contact lower electrode and a lead wire which grow on the upper part of the type layer, and a Schottky contact upper electrode and a lead wire which grow on the upper part of the N type layer; a manufacturing method of the variable capacitance diode is also provided. The varactor has flexible structure, high capacitance ratio, strong nonlinearity, high output power of millimeter wave frequency multiplier circuit and good high-frequency characteristic, and is easy to be applied in frequency multiplier circuit. This document does not relate to photosensitive SiC heterojunction varactors and two-dimensional electron (hole) gas.
In the literature 18[ Formation of two-dimensional electron gaps in polytypic SiC surfaces-structures, Journal of Applied Physics, Vol.98, No.5(2005):023709-1-7.] semiconductor heterojunction 3C/4H-SiC, 3C/6H-SiC interfaces prepared by Molecular Beam Epitaxy (MBE) technique have two-dimensional electron gas (2DEG), mainly due to spontaneous polarization of the interfaces; the surface density of the 3C/4H-SiC heterojunction interface 2DEG is higher than that of the AlGaN/GaN heterojunction interface 2DEG, and the thickness of the barrier layer is insensitive to change. This document only relates to the two-dimensional electron (hole) gas of SiC heterojunctions, and is not concerned with photosensitive varactors.
Document 19[ Electron and hole definition in hetero-crystal SiC superstrate, Journal of the Physical Society of Japan, Vol.84, No.8(2015):084709-1-6.]Analysis suggests that, since Si is different from C in electronegativity, electrons are transferred from Si to C, causing spontaneous polarization in SiC in the hexagonal phase, forming spontaneous polarization charges; however, because of the high symmetry, the cubic phase of SiC has no spontaneous polarization. On the other hand, because of the band gap E of 3C-SiC g 2.39eV, band gap E of 4H-SiC g 3.26eV, 6H-SiCBand gap E g 3.02eV, 3C/4H-SiC, 3C/6H-SiC c The high-density two-dimensional electron gas (2DEG) and the high-density two-dimensional hole gas (2DHG) are stored in the interface potential wells of the 3C/4H-SiC and 3C/6H-SiC heterojunction in the room temperature environment, and the high-density two-dimensional electron gas (2DEG) is very suitable for High Electron Mobility Transistors (HEMTs). The paper only relates to two-dimensional electron (hole) gas of SiC heterogeneous junction superlattice, but research reports of related devices such as heterogeneous junction barrier varactor (HBV) and the like are not reported, and the related devices are not related to photosensitive varactor.
Through analyzing and summarizing relevant documents of the existing heterojunction barrier varactor, the photosensitive SiC heterojunction multi-barrier varactor which is the same as or similar to the photosensitive SiC heterojunction multi-barrier varactor or has an enlightening technical scheme is not found.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the prior art and provide a photosensitive SiC heterojunction multi-barrier varactor, the scheme is novel in innovative mechanism, the heterojunction multi-barrier varactor consisting of cubic phase silicon carbide (3C-SiC) and hexagonal phase silicon carbide (4H-SiC and 6H-SiC) is small in capacitance and high in withstand voltage, and the photosensitive SiC heterojunction multi-barrier varactor is suitable for the related fields of frequency doubling, electric tuning, parameter amplification, optical detection and the like.
In order to achieve the purpose, the technical scheme of the invention comprises N which are arranged in sequence + Type 3C-SiC substrate, at least one set of heterogeneous junctions, N + A type 3C-SiC contact layer;
the heterogeneous junction is composed of an N-type 3C-SiC modulation layer, an intrinsic 4H-SiC or 6H-SiC barrier layer and an N-type 3C-SiC modulation layer, wherein in the heterogeneous junction, the N-type 3C-SiC with a narrow band gap is a potential well, and the intrinsic 4H-SiC or intrinsic 6H-SiC with a wide band gap is a potential barrier;
a silicon dioxide protective layer is generated on the surface of the heterogeneous junction, and a shading layer is coated outside the silicon dioxide protective layer;
n is as follows + Type 3C-SiC substrate, N + Ohmic electrodes are respectively arranged on the outer surfaces of the type 3C-SiC contact layers;
N + and a light hole for photosensitive driving is arranged on the outer surface of the type 3C-SiC contact layer.
Further setting as said N + Carrier concentration range of type 3C-SiC substrate is 1.0 x 10 24 —9.0×10 25 Rice and its production process -3 Thickness range of 2.0-3.0X 10 -4 Rice, said N + The doping of the type 3C-SiC substrate is phosphorus doping.
The surface of the N-type 3C-SiC modulation layer is one of a silicon atom surface and a carbon atom surface, and the surface of the modulation layer is one of a positive axis and an off-axis; the carrier concentration range of the N-type 3C-SiC modulation layer is 1.0 multiplied by 10 22 —9.0×10 23 Rice made of glutinous rice -3 Thickness in the range of 1.0X 10 -8 —9.0×10 -7 And the doping of the N-type 3C-SiC modulation layer is phosphorus doping.
Further, the thickness of the intrinsic 4H-SiC barrier layer or the intrinsic 6H-SiC barrier layer is in the range of 1.0-9.0 x 10 -8 m, and is undoped.
It is further provided that the N-type 3C-SiC modulation layer has a carrier concentration range of 1.0 x 10 22 —9.0×10 23 Rice and its production process -3 Thickness range of 1.0X 10 -8 —9.0×10 -7 And the doping of the N-type 3C-SiC modulation layer is phosphorus doping.
It is further provided that the number of cycles of said heterogeneous structure is set according to the requirements of pressure resistance and capacity, and the number of cycles is 2-20.
Further setting is that N + The carrier concentration range of the type 3C-SiC contact layer is 1.0 multiplied by 10 24 —9.0×10 25 Thickness range of 1.0-5.0X 10 -7 Rice, this N + The type 3C-SiC contact layer is doped with phosphorus.
The electrode is a gold-nickel electrode formed by evaporation through an electron beam evaporation technology.
Further setting is that N + And a light transmission hole is carved in the middle of the surface of the type 3C-SiC contact layer, and the area of the light transmission hole ranges from 1/3 to 1/2 of the cross section area of the heterogeneous junction.
Further setting that a silicon dioxide protective layer is generated on the surface of the heterogeneous junction, and oxidizing the surface of the whole heterogeneous junction by adopting a thermal oxidation process to generate the silicon dioxide protective layer; the outer coating light shading layer is made of light-proof, non-conductive and corrosion-resistant resin.
The diode of the invention, wherein a plurality of heterogeneous junction barrier capacitors are contained in series, the equivalent capacitance of the whole variable capacitance diode is smaller than that of a single heterogeneous junction barrier capacitor, and the terminal voltage of the whole variable capacitance diode is larger than that of the single heterogeneous junction barrier capacitor. Namely, the heterogeneous multi-barrier varactor has small capacitance and high withstand voltage, and is suitable for the fields of high frequency and high power. In addition, light with proper wavelength (such as green light) is adopted to irradiate the heterogeneous junction, because the energy gap (Eg) of the 3C-SiC is equivalent to that of the green light, the 3C-SiC modulation layer absorbs the green light and converts the green light into photon-generated carriers, and the photon-generated carriers are stored in a 3C-SiC potential well with a narrow band gap; the forbidden band width values of the 4H-SiC and the 6H-SiC are larger than the energy value of the green light, the green light is not absorbed, and photo-generated carriers do not exist. The capacitance of the heterogeneous junction barrier capacitor formed in the illumination area is increased due to the increase of carriers in the potential well absorbing light; the carriers in the potential well of the non-illuminated region do not change, and therefore the capacitance of the barrier capacitor formed in the non-illuminated region does not change. Since the capacitors in the two regions are connected in parallel, the capacitance after light irradiation is increased, and the withstand voltage is not changed. The 3C/4H-SiC and 3C/6H-SiC heterogeneous junction multi-potential-barrier varactor disclosed by the invention is used as a novel microwave optoelectronic device and can be used for frequency doubling, electric tuning, parameter amplification, optical detection and the like.
Advantageous effects of the invention
The photosensitive SiC heterojunction multi-barrier varactor provided by the invention has the characteristics of capacitance-voltage relation which is symmetrical about 0 voltage and current-voltage relation which is odd symmetrical about 0 voltage, small capacitance, high withstand voltage, high capacitance change ratio, high cut-off frequency, wide dynamic load modulation range, illumination regulation capacitance and the like. The no-load circuit is used for odd harmonic multiplication without even harmonic, and the circuit design is simplified; the capacitance can be adjusted by utilizing the two-dimensional electron (hole) gas of the SiC heterogeneous junction, the bias voltage range is expanded, the capacitance-voltage relation is improved, and the conversion efficiency of carrier-odd harmonic is improved; the photo-capacitance type detector has higher sensitivity. The photosensitive SiC heterojunction multi-barrier varactor is suitable for frequency doubling, electric tuning, parameter amplification, optical detection and the like. The invention not only provides a single device, but also provides a design idea for the photoelectric integrated circuit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is within the scope of the present invention for those skilled in the art to obtain other drawings based on the drawings without inventive labor.
Fig. 1 is a schematic diagram of a photosensitive SiC heterojunction multi-barrier varactor provided in one embodiment of the present invention, in which (a) is a 3C/4H-SiC heterojunction multi-barrier varactor and (b) is a 3C/6H-SiC heterojunction multi-barrier varactor;
fig. 2 is a schematic diagram of an energy band and equivalent capacitor in a photosensitive SiC heterojunction multi-barrier varactor according to an embodiment of the present invention, in which (a) is a 3C/4H-SiC heterojunction and (b) is a 3C/6H-SiC heterojunction;
fig. 3 is a photosensitive silicon carbide heterojunction multi-barrier varactor according to a first embodiment of the present invention, which is equivalent to: when the lighting area is lighted, the middle variable capacitance diode of the lighting area and the edge variable capacitance diode of the non-lighting area are connected in parallel;
fig. 4 is a graph showing a capacitance-voltage relationship simulation of a photosensitive SiC heterojunction multi-barrier varactor including 2 and 4 periods (N)3C/ 4H/(N)3C-SiC heterojunction according to a first embodiment of the present invention at room temperature with and without light;
fig. 5 is a graph showing a current-voltage relationship simulation of a photosensitive SiC heterojunction multi-barrier varactor including 2 and 4 periods (N)3C/ 4H/(N)3C-SiC heterojunctions at room temperature with or without light according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.
Practice ofExample one
The first embodiment of the invention provides an electrode/N with a structure as shown in the attached figure 1(a) of the specification + Type 3C-SiC/N type 3C-SiC/intrinsic 4H-SiC/N type 3C-SiC/N + Type 3C-SiC/electrode-photosensitive SiC heterojunction multi-barrier varactor, comprising the following steps:
a1, selecting N + Type 3C-SiC substrate with carrier concentration range of 1.0 × 10 24 —9.0×10 25 Rice made of glutinous rice -3 And a thickness of about 2.0X 10 -4 Rice, said N + The doping of the type 3C-SiC substrate is phosphorus doping.
A2 at N + Growing an N-type 3C-SiC modulation layer on the type 3C-SiC substrate, wherein the surface of the modulation layer can be one of a Si atomic plane and a C atomic plane, and the surface of the modulation layer can be one of a positive axis and an off-axis; carrier concentration range of modulation layer 1.0 × 10 22 —9.0×10 23 Rice and its production process -3 Thickness range of 1.0X 10 -8 —9.0×10 -7 The modulation layer is doped with phosphorus, and can be grown by one of Molecular Beam Epitaxy (MBE) and Metal Organic Chemical Vapor Deposition (MOCVD) techniques.
A3, growing intrinsic 4H-SiC barrier layer on the N-type 3C-SiC modulation layer with thickness ranging from 1.0 to 9.0 × 10 -8 m, the intrinsic 4H-SiC barrier layer is not doped and can be grown by adopting one of MBE and MOCVD methods.
A4, growing N-type 3C-SiC modulation layer on the intrinsic 4H-SiC barrier layer, the carrier concentration range of the modulation layer is 1.0 multiplied by 10 22 —9.0×10 23 Rice and its production process -3 Thickness range of 1.0X 10 -8 —9.0×10 -7 The doping of the M and N type 3C-SiC modulation layer is phosphorus doping, and the M and N type 3C-SiC modulation layer can be grown by one of MBE and MOCVD methods.
A5, the period of intrinsic N-type 3C-SiC/ 4H-SiC/N-type 3C-SiC isomeric structure is determined according to the requirement of voltage resistance and capacity, and can be 2-20.
A6, redepositing N + Type 3C-SiC contact layer with carrier concentration range of 1.0 × 10 24 —9.0×10 25 Rice made of glutinous rice -3 Thickness range of 1.0-5.0X 10 -7 Rice, said redepositing of N + Type 3C-SiC contact layerIs phosphorus doped, N + The type 3C-SiC contact layer and the electrode form ohmic contact; n is a radical of hydrogen + The type 3C-SiC contact layer can be grown by one of MBE and MOCVD methods.
And A7, oxidizing the surface of the whole isomeric junction by adopting a thermal oxidation process to generate a silicon dioxide protective layer.
And A8, coating a light-proof, non-conductive and corrosion-resistant resin shading layer on the silicon dioxide protection layer on the whole surface of the heterogeneous junction.
A9 at N + Respectively evaporating gold nickel electrodes on the upper surfaces of the type 3C-SiC substrate and the contact layer, and etching N firstly + A silicon dioxide protective layer on the upper surface of the type 3C-SiC substrate and the contact layer; in N + The upper surfaces of the type 3C-SiC substrate and the contact layer are respectively provided with gold-nickel alloy electrodes by evaporation, and are respectively connected with the N in an ohmic manner + A type 3C-SiC substrate, a contact layer; the gold-nickel alloy electrode can be grown by adopting an electron beam evaporation technology by using gold-nickel alloy as a raw material.
And A10, adopting a corrosive liquid to corrode the shading layer on the gold-nickel electrode on the contact layer, and then corroding the middle part of the gold-nickel electrode on the contact layer to form a light through hole with the area range of 1/3-1/2 of the cross-sectional area of the isomeric junction.
Completing the above ten steps to obtain gold-nickel ohmic electrode/N + Type 3C-SiC/N type 3C-SiC/ 4H-SiC/N type 3C-SiC/N + A type 3C-SiC/gold nickel ohmic electrode-a photosensitive SiC heterojunction multi-barrier varactor.
Example two
The second embodiment of the invention provides an electrode/N with a structure as shown in the attached figure 1(b) of the specification + Type 3C-SiC/N type 3C-SiC/intrinsic 6H-SiC/N type 3C-SiC/N + The type 3C-SiC/electrode-photosensitive SiC heterojunction multi-barrier varactor comprises the following steps:
b1, selecting N + Type 3C-SiC substrate with carrier concentration in the range of 1.0 × 10 24 —9.0×10 25 Rice and its production process -3 Thickness of about 2.0X 10 -4 Rice, said N + The doping of the type 3C-SiC substrate is phosphorus doping.
B2 at N + Growing an N-type 3C-SiC modulation layer on the type 3C-SiC substrate, wherein the surface of the modulation layer can be one of a Si atomic plane and a C atomic plane, and the surface of the modulation layer can be one of a positive axis and an off-axis; carrier concentration range of modulation layer 1.0 × 10 22 —9.0×10 23 Rice and its production process -3 Thickness range of 1.0X 10 -8 —9.0×10 -7 The modulation layer is doped with phosphorus, and can be grown by one of MBE and MOCVD methods.
B3, growing intrinsic 6H-SiC barrier layer on the N-type 3C-SiC modulation layer with thickness ranging from 1.0 to 9.0 x 10 -8 The intrinsic 6H-SiC barrier layer is not doped, and can be grown by one of MBE and MOCVD methods.
B4, growing an N-type 3C-SiC modulation layer on the intrinsic 6H-SiC barrier layer, wherein the carrier concentration range of the modulation layer is 1.0 multiplied by 10 22 —9.0×10 23 Rice and its production process -3 Thickness range of 1.0X 10 -8 —9.0×10 -7 The doping of the M and N type 3C-SiC modulation layer is phosphorus doping, and the M and N type 3C-SiC modulation layer can be grown by one of MBE and MOCVD methods.
B5, the period of the intrinsic 6H-SiC/N type 3C-SiC isomeric structure is determined according to the requirements of voltage resistance and capacity, and can be 2-20.
B6, redepositing N + Type 3C-SiC contact layer with carrier concentration in the range of 1.0 × 10 24 —9.0×10 25 Rice and its production process -3 Thickness range of 1.0-5.0X 10 -7 Rice, said redepositing of N + The doping of the type 3C-SiC contact layer is phosphorus doping, N + The type 3C-SiC contact layer and the electrode form ohmic contact; n is a radical of hydrogen + The type 3C-SiC contact layer can be grown by one of MBE and MOCVD methods.
And B7, oxidizing the surface of the whole isomeric junction by adopting a thermal oxidation process to generate a silicon dioxide protective layer.
And B8, coating a light-proof, non-conductive and corrosion-resistant resin shading layer on the silicon dioxide protection layer on the whole surface of the heterogeneous junction.
B9 at N + Respectively evaporating gold nickel electrodes on the upper surfaces of the type 3C silicon carbide substrate and the contact layer, and etching N firstly + Silicon dioxide protection of type 3C silicon carbide substrate and upper surface of contact layerA layer; in N + The upper surfaces of the type 3C silicon carbide substrate and the contact layer are respectively evaporated with gold nickel alloy electrodes which are respectively connected with the N in an ohmic manner + A type 3C silicon carbide substrate, a contact layer; the gold-nickel alloy electrode can be grown by adopting an electron beam evaporation technology by using gold-nickel alloy as a raw material.
B10, etching the shading layer on the gold-nickel electrode on the contact layer by using an etching solution, and etching the middle part of the gold-nickel electrode on the contact layer to form a light through hole with the area range of 1/3-1/2 of the cross-sectional area of the heterogeneous junction.
Completing the above ten steps to obtain gold-nickel ohmic electrode/N + Type 3C-SiC/N type 3C-SiC/ 6H-SiC/N type 3C-SiC/N + A type 3C-SiC/gold nickel ohmic electrode-a photosensitive SiC heterojunction multi-barrier varactor.
When the embodiment of the invention models and simulates the photosensitive SiC heterogeneous junction multi-barrier varactor, the electrode/N + Type 3C-SiC/N type 3C-SiC/intrinsic 4H-SiC/N type 3C-SiC/N + The structure of the type 3C-SiC/electrode is shown in the attached figure 1(a) of the specification. In the basic equations (poisson equation, current density equation and continuity equation) of the semiconductor device for describing the photosensitive SiC heterojunction multi-barrier varactor, besides the drift and diffusion mechanisms of carriers (electrons and holes), the spontaneous polarization effect of a 3C/4H-SiC heterojunction interface in the heterojunction multi-barrier varactor and the photon-generated carrier effect are also taken into account.
In a specific embodiment of the present invention, a poisson equation to which the conduction of carriers (electrons, holes) in a photosensitive SiC heterojunction multi-barrier varactor should adhere is given by formula (1):
wherein E (x) is an electric field, N (x), P (x) are an electron concentration and a hole concentration, respectively, ε is a dielectric constant, and q is 1.6 × 10 -19 Coulomb is the basic charge, N D 、N A Is the concentration of the doping impurities, and pi (x) is the electric polarization. Since the first embodiment of the invention only relates to 3C/4H-SiC isomeric junctions, albeit in the hexagonal phase4H-SiC comprises spontaneous polarization and piezoelectric polarization, but cubic phase 3C-SiC only has spontaneous polarization because of higher symmetry; and because the interface mismatch of the 3C/4H-SiC isomeric junction is less than 0.1%, the piezoelectric polarization caused by the interface mismatch is ignored, and the P (x) in the formula (1) only contains spontaneous polarization. For homojunctions or heterojunctions, heterogeneous junctions with no interfacial polarization, ii (x) ═ 0.
Therefore, the total free charge amount of a 3C/4H-SiC isomeric junction interface in the photosensitive silicon carbide isomeric junction multi-barrier varactor, namely the density [ n ] of a two-dimensional electron gas (2DEG), can be obtained by solving a Poisson equation and a Schroer's quota equation in an adaptive mode 2 (x)]And three-dimensional electron density [ n ] 3 (x)]The sum of (a) and (b). The poisson equation is listed as formula (1), the schroer's quota equation is listed as formula (2),
in the formula
Is reduced Planck constant, m ∥ * (x) For the electron effective mass in the vertical junction direction (x) in relation to position, V (x) is the electron potential, i.e. the conduction band edge, i is the number of quantized energy levels, F i Is the energy of the ith quantized level, Ψ i Is a wave function. The specific embodiment of the invention is the density [ n ] of two-dimensional electron gas (2DEG) in the photosensitive SiC heterojunction multi-barrier varactor 2 (x)]The column is shown as formula (3),
where k is Boltzmann's constant, m ⊥ * (x) For the position-dependent electron effective mass in the direction perpendicular to x, v is the number of equivalent conduction band minima, E F Is energy of the Fermi level, E sep Is the separation energy and T is the thermodynamic temperature. The specific embodiment of the invention is three-dimensional electron of a heterogeneous junction in a photosensitive SiC heterogeneous junction multi-barrier varactorDensity [ n ] 3 (x)]The column is shown as formula (4),
n 3 (x)＝N c f 12 (η,b), (4)
in the formula N c Is the three-dimensional effective density of states of the conduction band, f 1/2 (η, b) is the incomplete fermi integral.
Embodiments of the invention an electron current density (J) to which carrier conduction should adhere in a photosensitive SiC heterojunction multi-barrier varactor n ) Hole current density (J) p ) The equations are respectively listed as equations (5) and (6),
in the formula v n 、v p Drift velocity, μ, of electrons and holes, respectively n 、μ p Mobility of electrons and holes, respectively, D n 、D p The diffusion coefficients of electrons and holes, respectively. The first term on the right side of the signals in the equations (5) and (6) is a drift current portion, the second term is a diffusion current portion, and the third term is a Bohm potential H caused by the density gradient of electrons and holes n 、H p The fourth term, relative current density, is the photo-generated electron, hole current density. Bohm potential H of electron and hole n 、H p Are respectively listed as formulas (7) and (8):
coefficient of equation s p 、s n Is a function of the coefficient of the material,
r p(n) for statistically significant dimensionless quantities, r for SiC semiconductor devices suitable for high-temperature operation p 、r n And taking 3.
The photo-generated electron and hole current densities caused by light irradiation can be analyzed as follows.
Luminous power of P at wavelength of lambda in The effective illumination area is A i Then the photon flux surface density column is given by equation (9),
wherein R' (x) [ n ] s (λ)-n a (λ)]/[n s (λ)+n a (λ)]Is the reflectivity of the semiconductor material, n s (lambda) and n a (λ) is the refractive index of light of wavelength λ in semiconductor and air. Known illumination power P in In the embodiment of the invention, the generation rate of the electron-hole pair (e-h-p) at any point x in the 3C-SiC region absorbing light in the photosensitive SiC heterojunction multi-barrier varactor is listed as formula (10),
G L (λ)＝η in (λ)α(λ)φ 0 (λ)exp[-α(λ)x], (10)
in the formula eta in (λ) and α (λ) are the internal quantum efficiency and the absorption coefficient of 3C-SiC, respectively, for light of wavelength λ. The photo-generated electron current density J caused by illumination with a wavelength λ oe The column is a formula (11),
J oe (x)＝-q∫G L (λ)dx＝qη in (λ)φ 0 (λ){exp[α(λ)x n+ ]-exp[-α(λ)x p+ ]}, (11)
in the formula x n+ And x p+ Are respectively N + /N、N/N + The location of the interface.
Generally, the photo-generated electron current density J oe And photo-generated hole current density J oh Equal in size and opposite in direction, namely:
J oe ＝-J oh , (12)
because the N of the photosensitive SiC heterojunction multi-barrier varactor of the first embodiment of the invention + Type substrate, N + The electric field in the type contact layer is zero and the current is generated by diffusion in these 2 regions. By solving a one-dimensional bipolar transmission equation satisfying appropriate boundary conditions, the equation can be obtained at N + Type substrate, N + The current densities of the photo-generated electrons and holes of the type contact layer are listed as formulas (13) and (14),
in the formula L e 、L h The diffusion lengths of the electrons and holes, respectively.
Including displacement current density
In this case, the total current density is given by equation (15),
the electron current density (J) to which the conduction of carriers in the photosensitive SiC heterojunction multi-barrier varactor of the first embodiment of the invention should comply n ) Hole current density (J) p ) Are respectively listed as equations (16) and (17),
the distribution of the electric field intensity e (x) can be obtained by simultaneously solving equations (1), (5), (6), (16), and (17). The energy W stored in the capacitor can be calculated using the following equation (18),
therefore, the capacitance C of a photosensitive SiC heterojunction multi-barrier varactor, which is an embodiment of the present invention, can be calculated as formula (19),
of course, the capacitance C can also be obtained by calculating the charge amount of the anode or the cathode of the equivalent capacitance of the photosensitive SiC heterojunction multi-barrier varactor according to the embodiment of the invention,
Q n ＝∑∫ρdV+∑n 2 ＝∑∫q(P-N+N D -N A )dV+∑n 2 , (20)
in the specific embodiment of the invention, the capacitance C of the photosensitive SiC heterojunction multi-barrier varactor is listed as a formula (21),
in a parameter used in numerical calculation of one embodiment of the present invention, N + The thicknesses of the type 3C-SiC substrate and the N-type 3C-SiC modulation layer were 5.0X 10, respectively -6 Rice, 2.0X 10 -7 The thickness of the intrinsic 4H-SiC barrier layer is 3.0 x 10 -8 Rice, N + The doping concentrations of the type 3C-SiC substrate and the N-type 3C-SiC modulation layer are respectively 1.0 multiplied by 10 25 Rice and its production process -3 、2.0×10 22 Rice and its production process -3 The radius of the isomeric structure is 4.0 multiplied by 10 -4 Rice 4.0 x 10 2 The parameters for micron, 3C-SiC, 4H-SiC material are from the website http:// www.ioffe.rssi.ru/SVA/NSM/semiconductor/index. The boundary condition is mainly formed by the continuity of an electric field at the interface of a heterogeneous junctionSex determination;
the electronic wave function in the equation is treated as a plane wave, and when the plane wave reaches the heterogeneous junction interface, one part is reflected, and the other part is transmitted. The capacitance-voltage (C-V) relationship of the 3C/4H-SiC heterojunction multi-barrier varactor obtained by numerical simulation is shown in FIG. 4. Wherein, the 0 bias capacitance of the 2, 4 period 3C/4H-SiC heterogeneous junction multi-barrier varactor is only 10 pF, which is very small; the capacitance of the 2-period heterogeneous junction is greater than that of the 4-period heterogeneous junction, and it can be understood from fig. 2 that the smaller the period of the heterogeneous junction included in the varactor, the smaller the number of capacitors connected in series, and the larger the equivalent capacitance; when the bias voltage is close to +/-3V, the capacitance value of each varactor diode approaches to 0 because the depletion region of each varactor diode is almost completely depleted and the net residual charge approaches to 0, so the capacitance value approaches to 0; when light is emitted, the capacitance is larger, and it can be understood from fig. 2 that photogenerated carriers formed by absorbing green light by 3C-SiC in the 3C/4H-SiC heterogeneous junction of the light emitting region just fall in the 3C-SiC well region, part of the carriers are reduced due to heat dissipation, recombination and the like, and the net charge amount of the well region is increased by the rest of the carriers, so that the capacitance value is increased, as shown in fig. 4; the 2DEG caused by spontaneous polarization of the heterogeneous junction interface increases the net charge amount of the well region, so that the capacitance value is increased, and the capacitance value is not obviously increased because the value of the 2DEG is very small and is not shown in fig. 4; in the voltage range of 0 to +/-3V, the capacitance change is not severe, and the amplitude of an input signal can be larger no matter the input signal is used for a frequency multiplier, a tuner and a parameter amplifier, namely the dynamic load modulation range is wide.
In the first embodiment of the invention, a current-voltage (I-V) relation curve of the 3C/4H-SiC heterojunction multi-barrier varactor obtained through numerical simulation is shown in FIG. 5. The current of the 2-period heterojunction diode is larger than that of the 4-period heterojunction diode, and it can be understood that the smaller the period of the heterojunction included in the varactor diode, the smaller the number of resistors connected in series, the smaller the equivalent resistance value, and thus the larger the current intensity. The current is larger when light is irradiated, and it can be understood that the photogenerated carriers generated in the 3C-SiC well by the light irradiation increase the total number of carriers to be conducted, so the current intensity increases. At high voltage, the charge crossing the 3C/4H-SiC isomeric junction potential barrier is obviously increased, and the photon-generated carrier effect is relatively weakened; therefore, when the voltage is higher, the difference of I-V relation curves with or without illumination is not obvious. In the voltage range of 0-3V, the capacitance change is not severe, and the amplitude of the input signal can be larger no matter the input signal is used for a frequency multiplier, a tuner and a parameter amplifier, namely the dynamic load modulation range is wide.
With respect to document [7 ]]The capacitance modulation ratio C of the photosensitive SiC heterojunction multi-barrier varactor max /C min Leakage current J 0 Smaller, and is more suitable for the requirements of high frequency and high power.
The embodiment of the invention has the following beneficial effects:
(1) due to the advantages of the SiC material, the photosensitive SiC heterojunction multi-barrier varactor disclosed by the invention has the advantages of small capacitance, high withstand voltage, high varactor ratio, high cut-off frequency, wide dynamic load modulation range, approximate linear adjustment and the like;
(2) the photosensitive SiC heterogeneous junction multi-potential barrier varactor designed in the first embodiment of the invention has the characteristic that the capacitance-voltage relationship is symmetrical about 0 voltage, and an idle circuit of even harmonic is not needed in an odd harmonic frequency doubling circuit, so that the circuit design is simplified;
(3) according to the embodiment I, the capacitance-voltage relation is regulated and controlled by using the traditional factors such as the heterojunction barrier height, the potential well width and the like, the capacitance can be regulated and controlled by using the spontaneous polarization effect and illumination of the SiC heterojunction, and the design freedom degree of the heterojunction barrier varactor is increased;
(4) in the embodiment of the invention, the relationship between the capacitance and the voltage is observed to be changed by illumination, namely: under the illumination condition, the illumination condition can be reflected through the change of the capacitance-voltage relation caused by illumination, namely, the embodiment of the invention is also a capacitance type light detector, and has high light detection sensitivity;
(5) the embodiment of the invention not only provides a single device, but also provides a thought for photoelectric integration.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (10)
1. A photosensitive SiC heterojunction multi-barrier varactor is characterized in that:
comprising N arranged in sequence + Type 3C-SiC substrate, at least one set of heterogeneous junctions, N + A type 3C-SiC contact layer;
the heterogeneous junction is composed of an N-type 3C-SiC modulation layer, an intrinsic 4H-SiC or 6H-SiC barrier layer and an N-type 3C-SiC modulation layer, wherein in the heterogeneous junction, the N-type 3C-SiC with a narrow band gap is a potential well, and the intrinsic 4H-SiC or intrinsic 6H-SiC with a wide band gap is a potential barrier;
a silicon dioxide protective layer is generated on the surface of the heterogeneous junction, and a shading layer is coated outside the silicon dioxide protective layer;
said N is + Type 3C-SiC substrate, N + Ohmic electrodes are respectively arranged on the outer surfaces of the type 3C-SiC contact layers; n is a radical of + And the outer surface of the type 3C-SiC contact layer is provided with a light hole.
2. The photosensitive SiC heterojunction multi-barrier varactor of claim 1, wherein: said N is + Carrier concentration range of type 3C-SiC substrate is 1.0 x 10 24 —9.0×10 25 Rice and its production process -3 Thickness range of 2.0-3.0X 10 -4 Rice, said N + The doping of the type 3C-SiC substrate is phosphorus doping.
3. The photosensitive SiC heterojunction multi-barrier varactor of claim 1, wherein: the surface of the N-type 3C-SiC modulation layer is one of a silicon atom surface and a carbon atom surface, and the surface of the modulation layer is one of a positive axis and an off-axis; the carrier concentration range of the N-type 3C-SiC modulation layer is 1.0 multiplied by 10 22 —9.0×10 23 Rice and its production process -3 Thickness in the range of 1.0X 10 -8 —9.0×10 -7 The doping of the N-type 3C-SiC modulation layer is phosphorus doping。
4. The photosensitive SiC heterojunction multi-barrier varactor of claim 1, wherein: the surface of the intrinsic 4H-SiC or intrinsic 6H-SiC barrier layer is one of a silicon atom surface and a carbon atom surface, and the surface of the barrier layer is one of a positive axis and an off-axis; the intrinsic 4H-SiC barrier layer or the intrinsic 6H-SiC barrier layer has a thickness in the range of 1.0-9.0 x 10 -8 m, and is undoped.
5. The photosensitive SiC heterojunction multi-barrier varactor of claim 1, wherein: the surface of the N-type 3C-SiC modulation layer is one of a silicon atom surface and a carbon atom surface, and the surface of the modulation layer is one of a positive axis and an off-axis; the carrier concentration range of the N-type 3C-SiC modulation layer is 1.0 multiplied by 10 22 —9.0×10 23 Rice and its production process -3 Thickness range of 1.0X 10 -8 —9.0×10 -7 And the doping of the N-type 3C-SiC modulation layer is phosphorus doping.
6. The photosensitive SiC heterojunction multi-barrier varactor of claim 1, wherein: the number of the cycles of the isomeric junctions is set according to the requirements of pressure resistance and capacity, and the number of the cycles is 2-20.
7. The photosensitive SiC heterojunction multi-barrier varactor of claim 1, wherein: said N is + The carrier concentration range of the type 3C-SiC contact layer is 1.0 multiplied by 10 24 —9.0×10 25 Thickness range of 1.0-5.0X 10 -7 Rice, this N + The type 3C-SiC contact layer is doped with phosphorus.
8. The photosensitive SiC heterojunction multi-barrier varactor of claim 1, wherein: the electrode is a gold-nickel electrode formed by evaporation through an electron beam evaporation technology.
9. A photosensitive SiC heterojunction polymer as claimed in claim 1A barrier varactor, characterized by: said N is + The outer surface of the type 3C-SiC contact layer has a light transmission hole, and the area of the light transmission hole ranges from 1/3 to 1/2 of the cross section area of the heterogeneous junction.
10. The photosensitive SiC heterojunction multi-barrier varactor of claim 1, wherein: generating a silicon dioxide protective layer on the surface of the isomeric junction, and oxidizing the surface of the whole isomeric junction by adopting a thermal oxidation process to generate the silicon dioxide protective layer; the outer coating light shading layer is made of light-proof, non-conductive and corrosion-resistant resin.
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