CN209691770U - It is a kind of to be passivated enhanced low-dimensional nanometer detection device using hafnium oxide - Google Patents

Abstract

Enhanced low-dimensional nanometer detection device is passivated using hafnium oxide this patent discloses a kind of, device architecture substrate is followed successively by oxide skin(coating), Nano semiconductor layer, source electrode from bottom to top, for drain electrode respectively in Nano semiconductor layer two sides, Nano semiconductor layer rest part is passivated dielectric layer covering.Device preparation step is that the ultra-thin CdS nano-ribbons grown with CVD method are transferred on the silicon substrate with oxide skin(coating), source, drain electrode are made using techniques such as electron beam exposure and thermal evaporations, then it recycles the techniques such as electron beam exposure and atomic layer deposition to make hafnium oxide passivation dielectric layer, is prepared into low-dimensional nano photodetectors.The detector has the characteristics that highly sensitive, dark current is small, stability is good, low-power consumption and wide spectrum detect.

Description

It is a kind of to be passivated enhanced low-dimensional nanometer detection device using hafnium oxide

Technical field

This patent is related to a kind of low-dimensional nano photodetectors part, refers specifically to a kind of enhanced low using hafnium oxide passivation Wiener rice detector.

Background technique

Quasi- one dimension semiconductor nanobelt is due to the surprise with the physical and chemical performances such as special light, electricity, magnetic and nanostructure Characteristic can be increasingly becoming world community researcher's focus of attention.About the research of low-dimensional nano structure material, either The controlledly synthesis of material, the preparation of device, or the research etc. of low dimensional physics being directly linked with size, links are all also deposited In many problems to be solved.Wherein cadmium sulfide (CdS) is used as typical quasi one-dimensional material, typical direct band gap (2.4eV) II-VI group compound semiconductor materials, they have more special photoelectric conversion property, while also referred to as the Three generations's optoelectronic semiconductor material, is widely used in the high-tech areas such as signal detection, liquid crystal display and solar battery. Based on the photodetector of these semiconductor nano-strips because its big specific surface area, surface state and lattice defect can generate high sheet Carrier concentration is levied, causes device that there is biggish dark current to a certain extent, to seriously affect the optical detection of device Performance.Therefore, there is an urgent need to study a kind of unique device architecture to solve cadmium sulfide defect bring intrinsic carrier to drop Low-dark current, to improve the signal-to-noise ratio and detectivity of device.

To solve the above-mentioned problems, this patent proposes a kind of utilization hafnium oxide (HfO based on CdS₂) passivation enhancing The single nanobelt low-dimensional nanometer detection device and preparation method of type.This method be CdS channel it is upper all covering it is one layer very thin HfO₂, using hafnium oxide to passivation, the defect of material surface is reduced, the electron concentration for inhibiting defect state to generate, to come Regulate and control device threshold voltage, successfully inhibits dark current, commutating ratio with higher, higher detectivity and response rate.

Summary of the invention

This patent provides a kind of low-dimensional nano photodetectors part based on CdS, refers specifically to a kind of using hafnium oxide It is passivated enhanced low-dimensional nanometer detection device.

Above-mentioned patent is utilized in CdS nanometers of belt surface deposit hafnium oxides, is passivated to the surface defect of nanobelt, greatly Part of the surface defect is repaired, and be cannot function as carrier donor, is reduced intrinsic carrier, thus greatly reduces detector The purpose of dark current under no grid voltage, photodetector realize low-dark current, and detectivity is high, low-power consumption.

The structure of the detector are as follows: have SiO on p-type Si substrate 1₂Oxide layer 2, in SiO₂There is CdS to receive in oxide layer Rice band 3, left and right ends production source electrode 4 and drain electrode 5 on CdS nanobelt deposit on CdS nanobelt among the source electrode and drain electrode blunt Change dielectric layer 6；

The p-type Si substrate 1 is boron heavy doping；

The SiO₂The thickness of oxide layer 2 is 280 nanometers；

The thickness of the CdS nanobelt 3 is 50~80 nanometers, and length and width are 10~20 microns, 2 microns respectively；

The source electrode 4 and drain electrode 5 is Cr and Au electrode, and lower layer Cr is with a thickness of 15 nanometers, and upper layer Au is with a thickness of 45 nanometers.

The top passivation dielectric layer 6 is HfO₂, thickness is 20 nanometers.

Device preparation method the following steps are included:

1) grows CdS nanobelt using Au particulate catalytic in pure Si on piece using chemical vapor deposition (CVD) method, leads to CdS nanobelt is transferred to SiO by the method for crossing physical transfer₂On/Si substrate；

2) utilizes electron beam exposure EBL technology, and the technologies such as thermal evaporation and removing are in the upper of the CdS nanobelt shifted in advance Deposition chromium and gold electrode is accurately positioned in side, for the source of doing, drain electrode；

3) utilizes electron beam exposure EBL technology, and the technologies such as atomic layer deposition and removing are in transfer CdS nanobelt in advance Whole deposition hafnium oxide dielectric layers of surface channel are prepared into enhanced list to be passivated to CdS nanometers of belt surfaces Root nanobelt low-dimensional photodetector.

Because defect or trap can generate high intrinsic carrier concentration in CdS nanobelt, under certain source and drain bias, Thermoelectron caused by these intrinsic carriers and tunnelling current form biggish channel current i.e. dark current.Under illumination, when When the energy of incident photon is greater than the forbidden bandwidth of cadmium sulfide, the photo-generate electron-hole of generation is separated under applying bias, from It will form photogenerated current, the electric current collected at this time is the summation of dark current and photogenerated current.Using hafnium oxide to CdS nanobelt Surface defect be passivated, most surfaces defect is repaired, and cannot function as carrier donor, reduces intrinsic current-carrying Son, to make the dark current of detector drop to pA hereinafter, realizing dark current of obviously drawing up.Hafnium oxide is in cadmium sulfide table simultaneously Face has completely cut off material and has contacted with the water oxygen in air, maintained the stability of CdS material.Therefore enhanced after this passivation The channel current of single nanobelt detector under light illumination is mainly formed generated photogenerated current by photo-generate electron-hole , since dark current has obtained effective inhibition, to substantially increase the signal-to-noise ratio and detectivity of device.

The advantages of this patent patent, is:

Whole covering one layer very thin HfO of this patent in CdS nanobelt channel₂, using hafnium oxide to material surface Defect is passivated, and most surfaces defect is repaired, and cannot provide intrinsic carrier, to thus greatly reduce detection The dark current of device, improve the signal-to-noise ratio and response speed of device, the very good solution big disadvantage of CdS nanobelt dark current. Based on this method, the single device sensitive detection parts of CdS nano-ribbons, dark current can be to 10^-12A, response rate and detectivity can be with Stable is maintained at~10⁴A/W and~10¹⁵Jones。

Detailed description of the invention

Fig. 1 is the structural schematic diagram that enhanced single nanobelt low-dimensional photodetector is passivated based on CdS hafnium oxide.

In Fig. 1: 1P type Si substrate, 2SiO₂Oxide layer, 3CdS nanobelt, 4 source electrodes, 5 drain electrodes, 6 passivation dielectric layers.

Fig. 2 is the energy band schematic diagram of CdS, wherein (a) figure is the energy band schematic diagram before hafnium oxide Passivation Treatment, (b) figure For the energy band schematic diagram after hafnium oxide Passivation Treatment.

Fig. 3 be CdS nano-ribbons before and after passivation output characteristic curve figure in no light and under having illumination respectively.

Fig. 4 is that hafnium oxide is passivated enhanced single nanobelt low-dimensional photodetector under different incident optical powers Response rate and detectivity figure.

Specific embodiment

It elaborates with reference to the accompanying drawing to specific implementation of the patent mode:

This patent has developed hafnium oxide and is passivated enhanced single nanobelt low-dimensional photodetector.On CdS channel All one layer of very thin HfO of covering₂, System of Detecting Surface Defects For Material is passivated with hafnium oxide, most surfaces defect is repaired It is multiple, intrinsic carrier cannot be provided, to thus greatly reduce the dark current of detector, improve the signal-to-noise ratio and sound of device Answer speed, the very good solution big disadvantage of CdS nanobelt dark current, and meanwhile commutating ratio with higher, higher detectivity And response rate.

Specific step is as follows:

1. the selection of substrate

Select B heavily-doped p-type silicon as substrate, resistivity is 0.05 Ω cm, SiO₂Oxidated layer thickness is 280nm；

The production of 2.mark label

Mark figure is prepared on p-type silicon substrate using ultraviolet photolithographic method, prepares metal mark using thermal evaporation techniques, 15 nanometers of chromium, 45 nanometers of gold, in conjunction with conventional stripping methods, stripping metal film obtains metal mark label.

3. the preparation and transfer of material

CdS nanobelt, first thermal evaporation on a si substrate are prepared in pure silicon on piece using chemical vapor deposition (CVD) method Then CdS powder is placed in ceramic boat and is placed in quartz ampoule center, the tube furnace of quartz ampoule periphery by the Au film of 1nm thickness System can be heated.Si piece is lain on quartz boat, be put into togerther quartz ampoule airflow downstream away from powder 15cm at.It vacuumizes To 1 × 10^-1Pa, it is carrier gas that it is for argon gas and hydrogen (10%) the gaseous mixture work of 100sccm that system, which keeps flow, in reaction process, It begins to warm up from room temperature to 750 DEG C, air pressure maintains 200Pa, then keeps the temperature 50 minutes, after the completion of experiment, stops heating and holding It is continuous to be passed through carrier gas, allow reaction tube to naturally cool to room temperature.The nanobelt of growth SiO has been physically transferred to finally₂Oxide layer band On the p-type silicon substrate of mark.

4. preparing source, drain electrode

It is taken pictures at material by optical microscopy, the figure of hearth electrode is prepared using DesignCAD21 software design, used Sol evenning machine spin coating PMMA, revolving speed 4000 turns/min, time 40s, 170 degree of drying times are 5 minutes；It is right using electron beam exposure Electrode pattern carries out precise positioning exposure, is then developed with PMMA developer solution；Metal electrode is prepared using thermal evaporation techniques, 15 nanometers of chromium, 45 nanometers of gold；In conjunction with traditional stripping means, impregnated 10 minutes with acetone soln, stripping metal film, acquisition source, Drain electrode.

5. preparing HfO₂Dielectric layer

It is taken pictures at electrode by optical microscopy, then utilizes DesignCAD21 software design HfO on picture₂System Standby figure, graphics request cover CdS nanobelt channel whole region；Using with sol evenning machine spin coating PMMA, 4000 turns of revolving speed/ Min, time 40s, 170 degree of drying times are 5 minutes；Using electron beam exposure, precise positioning exposure is carried out to electrode pattern, so Developed afterwards with PMMA developer solution；HfO is deposited using technique for atomic layer deposition₂, 20 nanometers of thickness；In conjunction in conjunction with traditional stripping It from method, is impregnated 10 minutes with acetone soln, removing obtains HfO₂Dielectric layer.

6. Fig. 1 is device architecture schematic diagram.

7. the energy band schematic diagram that Fig. 2 is (a) and the CdS of (b) layer after processing before hafnium oxide Passivation Treatment.Because in nanobelt Defect or trap can generate high intrinsic carrier concentration, will lead to biggish dark current, to influence the detection performance of device. In order to realize the reduction to intrinsic carrier, one layer of very thin HfO is all covered on CdS channel₂, with hafnium oxide to material Surface defect is passivated, and most surfaces defect is repaired, and cannot provide intrinsic carrier, to thus greatly reduce The dark current of detector, improves the signal-to-noise ratio and response speed of device, and CdS nanobelt dark current is big lacks for very good solution Point, while commutating ratio with higher, higher detectivity and response rate.

8. Fig. 3 CdS nano-ribbons output characteristic curve in no light and under having illumination respectively before and after the passivation.Passivation Before, the photoswitch of CdS nano-wire photodetectors is than being respectively less than 1.After passivation, the dark current of nanobelt optical detector be down to pA with Under, photoswitch ratio I_phWith I_darkThe ratio between up to 10⁶To 10⁷, signal-to-noise ratio greatly improved.

9. Fig. 4 is that hafnium oxide is passivated enhanced single nanobelt low-dimensional photodetector under different incident optical powers Response rate and detectivity curve.It is equal for different channel lengths (6 μm to 12 μm) and thickness (50nm to 80nm), device Show that the photo absorption property of superelevation, response rate and detectivity formula are respectivelyD*=RA^1/2/ (2eI)^1/2。

A) hafnium oxide is passivated enhanced single nanobelt (2 μm of width, thickness 50nm, 12 μm of channel) low-dimensional photoelectricity Detector (photodetector near ultraviolet band (λ=450nm) detectivity up to 3 × 10¹³Jones；

B) hafnium oxide is passivated the spy of enhanced single nanobelt (2 μm of width, thickness 60nm, 9 μm of channel) low-dimensional photoelectricity Survey device (photodetector near ultraviolet band (λ=450nm) detectivity up to 2 × 10¹⁴Jones；

C) hafnium oxide is passivated the spy of enhanced single nanobelt (2 μm of width, thickness 80nm, 6 μm of channel) low-dimensional photoelectricity Survey device (photodetector near ultraviolet band (λ=450nm) detectivity up to 1 × 10¹⁵Jones。

As a result illustrate that this patent hafnium oxide is passivated enhanced single nanobelt low-dimensional photodetector and its preparation side The electron concentration of defect state generation can be effectively suppressed in method, the structure devices, to successfully press down to regulate and control device threshold voltage Dark current is made.The detector has the characteristics that highly sensitive, dark current is small, stability is good, low-power consumption and wide spectrum detect.

Claims (1)

1. a kind of be passivated enhanced low-dimensional nanometer detection device, including p-type Si substrate (1), SiO using hafnium oxide₂Oxide layer (2), Source electrode (4) and drain electrode (5), it is characterised in that:

The structure of the detector are as follows: have SiO on p-type Si substrate (1)₂Oxide layer (2), in SiO₂There is CdS to receive in oxide layer Rice band (3) left and right ends production source electrode (4) and drains (5) on CdS nanobelt, among the source electrode and drain electrode on CdS nanobelt It deposits passivation dielectric layer (6)；

The p-type Si substrate (1) is boron heavy doping, and resistivity is less than 0.05 Ω cm；

The SiO₂The thickness of oxide layer (2) is 280 nanometers；

The thickness of the CdS nanobelt (3) is 50~80 nanometers, and length and width are 10~20 microns, 2 microns respectively；

The source electrode (4) and drain electrode (5) is Cr and Au electrode, and lower layer Cr is with a thickness of 15 nanometers, and upper layer Au is with a thickness of 45 nanometers；

The passivation dielectric layer (6) is HfO₂, thickness is 20 nanometers.