p-Si/n-Ga_(2)O_(3)异质结制备与特性研究

本实验采用金属有机化学气相沉积(MOCVD)工艺,在p(111)型Si衬底上制备了p-Si/n-Ga_(2)O_(3)结构的PN结。通过X射线衍射仪、原子力显微镜等对样品进行了晶体结构、表面形貌、表面粗糙度等的表征分析;通过磁控溅射与蒸镀方法在样品上生长Ti/Au电极并进行I-V特性曲线、开启电压、开关电流比、反向饱和电流、理想因子、零偏压下的势垒高度等结特性测试,研究了掺杂浓度与薄膜厚度对PN结特性的影响,并对其原因进行了分析;通过二步生长法和缓冲层温度优化实验,减少了Si衬底与β-Ga_(2)O_(3)之间的晶格失配与热失配带来的影响,对薄膜与器件特性进行了优化。最终获得了表面粗糙度最低可达到4.21 nm的高质量n型β-Ga_(2)O_(3)薄膜,以及具有较低理想因子(42.1)的PN结。

基于Python的PN结物理特性实验数据处理方法

半导体PN结物理特性实验中的数据计算量大,如果使用普通计算器计算,不仅繁琐费时而且易引入误差.通过Python语言调用Numpy模块可实现对实验数据的多项式拟合,再通过Matplotlib模块可实现可视化绘图.结果表明,该方法能快速、准确处理实验数据,给出电流电压关系拟合曲线,对PN结实验数据的分析和处理有很好的辅助作用.

Visualizing light-to-electricity conversion process in InGaN/GaN multi-quantum wells with a p-n junction

Absorption and carrier transport behavior plays an important role in the light-to-electricity conversion process, which is difficult to characterize. Here we develop a method to visualize such a conversion process in the InGaN/GaN multiquantum wells embedded in a p-n junction. Under non-resonant absorption conditions, a photocurrent was generated and the photoluminescence intensity decayed by more than 70% when the p-n junction out-circuit was switched from open to short. However, when the excitation photon energy decreased to the resonant absorption edge, the photocurrent dropped drastically and the photoluminescence under open and short circuit conditions showed similar intensity. These results indicate that the escaping of the photo-generated carriers from the quantum wells is closely related to the excitation photon energy.

Photoelectric characteristics of silicon P–N junction with nanopillar texture:Analysis of X-ray photoelectron spectroscopy

Silicon nanopillars are fabricated by inductively coupled plasma （ICP） dry etching with the cesium chloride （CsCl） islands as masks originally from self-assembly. Wafers with nanopillar texture or planar surface are subjected to phosphorus （P） diffusion by liquid dopant source （POCl3） at 870 ℃ to form P-N junctions with a depth of 300 nm. The X-ray photoelectron spectroscopy （XPS） is used to measure the Si 2p core levels of P-N junction wafer with nanopillar texture and planar surface. With a visible light excitation, the P-N junction produces a new electric potential for photoelectric characteristic, which causes the Si 2p core level to have a energy shift compared with the spectrum without the visible light. The energy shift of the Si 2p core level is -0.27 eV for the planar P-N junction and -0.18 eV for the nanopillar one. The difference in Si 2p energy shift is due to more space lattice defects and chemical bond breaks for nanopillar compared with the planar one.

Thin Film of Perovskite Oxide with Atomic Scale p-n Junctions

Thin films of perovskite manganese oxide Lao.66Ca0.29K0.05MnO3（LCKMO） on Au/ITO（ITO=indium tin oxide） substrates were prepared by off-axis radio frequency magnetron sputtering and characterized by X-ray diffrac- tion（XRD）, high-resolution transmission electron microscopy（HRTEM）, and conductive atomic force microscopy （C-AFM） at room temperature. The thin films with thickness ranged from 100 nm to 300 nm basically show cubic structures with a=0.3886 nm, the same as that of the raw material used, but the structures are highly modulated. C-AFM results revealed that the atomic scale p-n junction feature of the thin films was the same as that of the single crystals. The preparation of the thin films thus further confirms the possibility of their application extending from micrometer-sized single crystals to macroscopic thin film.

Nonlinear Properties of an Inhomogeneous Diode Structure in a Strong Microwave Field

Results of experimental investigation of detection (rectification) of high power X-band microwave signal in diodes of various design (semiconductor p-n-junction, point-contact, Schottky, Metal-Isolator-Metal—MIM) are reported. The maximum of the detected direct voltage V vs. power P of microwave signal and subsequent polarity reversal, previously found in MIM diodes in the optical and microwave bands, have found to be characteristic of all investigated diodes as well. After the reversal of polarity, this dependence comes linear, and the sign of the voltage corresponds to thermoEMF. In some diodes, the hysteresis on V(P) was observed. All 5 types of V(P) of MIM diodes (have made from different pairs of metals), reported earlier, were reproduced on same p-n-junction diode by variable external DC bias. These results joined with abnormal frequency cutoff forced to suggest that there is an unknown mechanism for direct flow of charge carriers (and for generate direct current) in the high-frequency electrical field, which differs from the conventional rectification.

Research on high-voltage 4H-SiC P-i-N diode with planar edge junction termination techniques

The planar edge termination techniques of junction termination extension （JTE） and offset field plates and fieldlimiting rings for the 4H-SiC P i-N diode were investigated and optimized by using a two-dimensional device simulator ISE-TCAD10.0. By experimental verification, a good consistency between simulation and experiment can be observed. The results show that the reverse breakdown voltage for the 4H-SiC P-i-N diode with optimized JTE edge termination can accomplish near ideal breakdown voltage and much lower leakage current. The breakdown voltage can be near 1650 V, which achieves more than 90 percent of ideal parallel plane junction breakdown voltage and the leakage current density can be near 3 ×10^-5 A/cm2.

The influence of electronic transport across interface junction between Si substrate and the root of ZnO micro-prism on field emission performance

ZnO micro-prisms are prepared on the p-type and n-type Si substrates, separately. The Ⅰ-Ⅴ curves analysed by AFM show that the interface junctions between the ZnO micro-prisms and the p-type substrate and between the ZnO micro-prisms and the n-type Si substrate exhibit p-n junction behaviour and ohmic contuct behuviour, respectively. The formation of the p-n heterojunction and ohmic contact is ascribed to the intrinsic n-type conduction of ZnO material. Better field emission performance （lower onset voltage and larger emission current） is observed from an individual ZnO micro-prism grown on the n-type Si substrate. It is suggested that the n-Si/n-ZnO interracial ohmic contact benefits the electron emission; while the p-Si/n-ZnO interface heterojunction deteriorates the electron emission.

High-performance germanium n+/p junction by nickel-induced dopant activation of implanted phosphorus at low temperature

High-performance Ge n~＋/p junctions were fabricated at a low formation temperature from 325℃ to 400℃ with a metal（nickel）-induced dopant activation technique. The obtained Ni Ge electroded Ge n＋/p junction has a rectification ratio of 5.6×10~4 and a forward current of 387 A/cm^2at -1 V bias. The Ni-based metal-induced dopant activation technique is expected to meet the requirement of the shallow junction of Ge MOSFET.

Numerical simulation of the magnetoresistance effect controlled by electric field in p–n junction

The magnetoresistance effect of a p-n junction under an electric field which is introduced by the gate voltage at room temperature is investigated by simulation. As auxiliary models, the Lombardi CVT model and carrier generation- recombination model are introduced into a drift-diffusion transport model and carrier continuity equations. All the equa- tions are discretized by the finite-difference method and the box integration method and then solved by Newton iteration. Taking advantage of those models and methods, an abrupt junction with uniform doping is studied systematically, and the magnetoresistance as a function of doping concentration, SiO2 thickness and geometrical size is also investigated. The simulation results show that the magnetoresistance （MR） can be controlled substantially by the gate and is dependent on the polarity of the magnetic field.

Optoelectronic properties of bottom gate-defined in-plane monolayer WSe_2 p–n junction

Monolayer transition-metal dichalcogenides （TMDs） are considered to be fantastic building blocks for a wide variety of optical and optoelectronic devices such as sensors, photodetectors, and quantum emitters, owing to their direct band gap, transparency, and mechanical flexibility. The core element of many conventional electronic and optoelectronic devices is the p-n junction, in which the p- and n-types of the semiconductor are formed by chemical doping in different regions. Here, we report a series of optoelectronic studies on a monolayer WSe2 in-plane p-n photodetector, demonstrating a low- power dissipation by showing an ambipolar behavior with a reduced threshold voltage by a factor of two compared with the previous results on a lateral electrostatically doped WSe2 p-n junction. The fabrication of the device is based on a polycarbonates （PC） transfer technique and hence no electron-beam exposure induced damage to the monolayer WSe2 is expected. Upon optical excitation, the photodetector demonstrates a photoresponsivity of 0.12 mA.W-1 and a maximum external quantum efficiency of 0.03%. Our study provides an alternative platform for a flexible and transparent two- dimensional photodetector, from which we expect to further promote the development of next-generation optoelectronic devices.

Study on Porous Silicon with P-N Junction Sensor for Humidity Measurement

Porous materials used for humidity sensing have been commercialized.In this paper,the preparation and humidity sensing characteristics of porous silicon with P-N junctions (PNJPS)are studied.PNJPS is made by electro-chemical anodic etched method from silicon wafers with P-N junctions.Its porous structure is verified by scanning electronic micrograph. Experiments also show that PNJPS has high sensitivity,short response time (less than 30 seconds),and long-term stability.

Analyses and Simulation of V-I Characteristics for Solar Cells Based on P-N Junction

Through theoretical analyses of the Shockley equation and the difference between a practical P-N junction and its ideal model, the mathematical models of P-N junction and solar cells had been obtained. With Matlab software, the V-I characteristics of diodes and solar cells were simulated, and a computer simulation model of the solar cells based on P-N junction was also established. Based on the simulation model, the influences of solar cell’s internal resistances on open-circuit voltage and short-circuit current under certain illumination were numerically analyzed and solved. The simulation results showed that the equivalent series resistance and shunt resistance could strongly affect the V-I characteristics of solar cell, but their influence styles were different.

EMF of Hot Charge Carriers Arising at the p-n-Junction under the Influence of the Microwave Field and Light

It is shown that the increase in the current of an asymmetric p-n-junction, caused by perturbation of potential barrier height and increasing recombination current in a strong microwave field, is suppressed by light generated photo carriers, leading to the displacement of current-voltage characteristics of p-n-junction into the direction of smaller current values.

The Nonideality Coefficient of Current-Voltage Characteristics for Asymmetric p-n-Junctions in a Microwave Field

It is shown that the nonideality coefficient m actually depends on the electron temperature Te, and the hole temperature Th. We get more general expression for the nonideality coefficient, taking into account the concentration of electrons and holes, as well as their temperature, coefficient and diffusion length, the temperature of the phonons, the applied voltage, and the height of the potential barrier.

The Effect of Light on the CVC of Strained p-n-Junction in a Strong Microwave Field

For the first time the effect of light on the CVC of strained p-n-junction in a strong microwave field is examined. It is shown that the deformation and the microwave field increase the current through p-n-junction, and the light decreases it. The mechanism of this phenomenon is explained by the fact that under heating of the charge carriers by microwave field the recombination current arises, and under the action of light the generation current arises which are directed oppositely. And under the influence of the deformation the band gap of the semiconductor will be changed.

Influence of Deformation on CVC p-n-Junction in a Strong Microwave Field

This paper investigates the current-voltage characteristics (CVC) strain of p-n-junction in a strong microwave (MW) field and shows that the deformation increases the current generated in the p-n-junction. We analyze the current-voltage characteristics of p-n-junction in which three-dimensional space (I,U,e) gives more complete information than the two-dimensional.

硅p-n结太阳电池对DF激光的响应

对硅p n结太阳电池在DF激光辐照下的响应进行了理论和实验研究。推导了p n结反向饱和电流随温度的近似变化关系。根据该近似关系,计算了太阳电池在DF激光辐照过程中输出电压的变化曲线。计算结果和实验结果之间取得了比较好的一致性。

碲镉汞 p^+-on-n长波异质结探测器的研究

报道了HgCdTep+onn长波异质结焦平面器件的研究结果.采用由分子束外延(MBE)和原位掺杂技术生长的p+onn异质结材料,通过湿法腐蚀、台面钝化、台面金属化、铟柱制备和互连等工艺,得到了HgCdTep+onn长波异质结焦平面器件.根据IV实验结果和暗电流理论,拟合计算和分析了各种暗电流机制对器件性能的影响,且获得了器件的响应光谱和探测率.