透射式GaAS阴极粘结工艺的X射线双晶衍射研究

本文分析了透射式ＧａＡｓ阴极粘结工艺中应力产生的根源和晶体中的应力对Ｘ射线双晶衍射峰的宽度和强度的影响．用Ｘ射线双晶衍射仪测量了阴极和玻璃热粘结工艺过程中的阴极材料外延层和衬底的双晶摇摆曲线．结果表明，透射式ＧａＡｓ阴极热压粘结工艺带来明显的附加应力，外延层衍射半峰宽的展宽是由于热膨胀系数的差异导致阴极层非均匀应力引起的．     

氮化镓(GaN)阴极紫外微通道板光电倍增管

<正>南京电子器件研究所近期研制成功的氮化镓(GaN)阴极紫外光电倍增管,采用MOCVD方式外延生长的蓝宝石/AlN/P-AlGaN异质外延结构作为阴极衬底材料,通过真空转移设备的高铝P型GaN材料微结构设计和工艺流通、透射式异质阴极材料生长、GaN外延片洁净处     

NEA GaN光电阴极材料光学特性研究

针对NEA GaN光电阴极结构设计和制备工艺需进一步优化的问题,结合阴极量子效率表达式和影响量子效率的因素,采用理论和实验相结合的方法,分别研究了GaN光电阴极材料的表面反射率、光学折射率、光谱吸收系数以及透射光谱等光学参数。结果表明在250 nm到365 nm的波长范围内,表面反射率相对平稳,是影响量子效率的直接因素,而光学折射率则通过电子表面逸出几率间接影响着量子效率。给出了均匀掺杂GaN光电阴极的光谱吸收系数的特点,根据变掺杂NEA GaN光电阴极的结构特点,给出了光谱平均吸收系数的概念和等价计算公式,并对均匀掺杂与变掺杂NEA GaN光电阴极光谱吸收系数进行了对比。     

GaAs／GaAsAl阴极粘结X射线双晶衍射测量

分析了ＧａＡｓ／ＧａＡｓＡｌ阴极粘结工艺中应力产生的根源和晶体中应力对Ｘ射线双晶衍射峰的宽度和强度的影响，用Ｘ射线双晶衍射仪测量阴极和玻璃热粘结工艺过程中的阴极材料外延层和衬底的双晶回摆曲线，实验结果表明，ＧａＡｓ／ＧａＡｓＡｌ阴极粘结工艺没有带来明显的附加应力，外延层衍射角的展宽是由于ＧａＡｓ阴极组件窗玻璃的非晶态性所致。     

负电子亲和势氮化镓光电阴极

负电子亲和势GaN光电阴极在紫外探测技术领域具有诱人的应用前景.本文在介绍和分析负电子亲和势GaN光电阴极的特点、工作原理及其能带结构的基础上,设计了GaN外延材料的结构和阴极制作工艺.指出负电子亲和势GaN光电阴极制备的关键在于材料的生长、与输入光窗的融焊、衬底的减薄及彻底的去气处理和超高真空状态下的铯、氧激活.     

透射式GaAs（Cs,O）光电阴极发射电子横向能量的研究

制备了透射式ＧａＡｓ阴极组件,测量了ＧａＡｓ阴极激活过程中阴极光 敏度和发射电子平均横向能量随激活时间的变化,用扫描电镜观察ＧａＡｓ（Ｃｓ,Ｏ）阴极表面形貌,结果表明：ＧａＡｓ（Ｃｓ,Ｏ）阴极发射电子横向能量取决于ＧａＡｓ晶格温度、阴极表面形貌和电子在能带弯曲区的多次散射,与（Ｃｓ,Ｏ）激活层无关。     

NEA GaN光电阴极的制备及其应用

近年来,随着晶体生长技术的发展,GaN基材料的生长技术与生长工艺取得了重大突破.基于NEA的GaN紫外光电阴极是非常理想的新型紫外光电阴极.本文重点探讨了NEA GaN光电阴极材料的金属有机化学汽相沉积(MOCVD)、分子束外延(MBE)和卤化物汽相外延(HVPE)等主流生长技术的优缺点,介绍了两步生长、横向外延生长及悬空外延技术等新工艺.讨论了GaN光电阴极的性能特点、制备方法以及在紫外光电探测器和电子束平版印刷术领域的应用状况.     

垂直结构GaN基LEDs热压键合应力损伤分析

热压键合是垂直结构LED制备的关键工艺步骤,通过TEM,PL,Raman等测试手段,探讨热压键合造成的应力损伤、GaN材料缺陷、LED内量子效率以及反向漏电间的内在联系,研究以键合引起的应力诱导垂直结构GaN基LED光电特性的退化机制,探讨应力损伤对垂直结构GaN基LED光电特性的影响.实验结果表明,热压键合过程会在GaN材料内产生GPa量级的残余应力,在量子限制strark效应作用下,GaN材料辐射复合效率发生明显退化;同时热压键合应力还会诱发GaN材料位错密度的增加,最终导致LED反向漏电增大.     

近红外响应的III-V族半导体光电阴极材料及工艺

随着GaAs负电子亲和势(NEA)半导体光电阴极在我国的成熟和应用,半导体光电阴极的进一步研究将往更长波的近红外发展。针对透射式半导体光电阴极器件,系统总结了近红外波段响应良好的GaAs、InGaAs、InGaAsP Ⅲ-V族外延材料特性及相应商业化产品的应用领域和性能。通过文献调研本文进一步归纳了不同波段NEA光电阴极和转移电子光阴极适用的材料结构,并结合传统GaAs NEA光电阴极工艺讨论了InGaAs、InGaAsP材料及阴极工艺的难点。     

近红外响应的Ⅲ-V族半导体光电阴极材料及工艺北大核心

随着GaAs负电子亲和势(NEA)半导体光电阴极在我国的成熟和应用,半导体光电阴极的进一步研究将往更长波的近红外发展。针对透射式半导体光电阴极器件,系统总结了近红外波段响应良好的GaAs、InGaAs、InGaAsP Ⅲ-V族外延材料特性及相应商业化产品的应用领域和性能。通过文献调研本文进一步归纳了不同波段NEA光电阴极和转移电子光阴极适用的材料结构,并结合传统GaAs NEA光电阴极工艺讨论了InGaAs、InGaAsP材料及阴极工艺的难点。     

GaN紫外光电导探测器的研究

回顾了近几年在 Ga N紫外光电导探测器上的研究进展 ,介绍了不同 Ga N光电导紫外光探测器的制备方法、光电参数及工作机理。     

Improved detection of the invisible

The ultraviolet (UV) portion of the spectrum is widely used for a variety of sensing and imaging applications. However, until very recently, with the advent of wide-bandgap materials such as AlGaN, there have not been high-performance optoelectronic devices designed for optimal operation in the UV range. Thus, the development of sophisticated detection applications in the UV range has been limited by the existing technology. This article outlines recent advances in the development of high-quality UV photodetectors fabricated on GaN and AlGaN. Several specific device structures and their performance characteristics are also presented     

基于斜台面工艺的背照式GaN雪崩探测器制备

为了获得高功率高光束质量激光输出,设计并制备了一种780nm波段5发光单元列阵器件,其采用10μm宽窄条形波导,各发光单元中心间距为100μm,填充因子仅为10%。在准连续注入电流由1.2A增加到2.5A条件下,该器件的输出光束侧向光学参量积由0.666mm·mrad增加至0.782mm·mrad。注入电流为2.5A时,该器件实现了单边准连续506mW的高光束质量激光输出。 更多还原     

Exfoliation of Threading Dislocation‐Free,Single‐Crystalline,Ultrathin Gallium Nitride Nanomembranes

Despite the recent progress in gallium nitride (GaN) growth technology, the excessively high threading dislocation (TD) density within the GaN crystal, caused by the reliance on heterogeneous substrates, impedes the development of high‐efficiency, low‐cost, GaN‐based heterostructure devices. For the first time, the chemical exfoliation of completely TD‐free, single‐crystalline, ultrathin (tens of nanometers) GaN nanomembranes is demonstrated using UV‐assisted electroless chemical etching. These nanomembranes can act as seeding layers for subsequent overgrowth of high‐quality GaN. A model is proposed, based on scanning and transmission electron microscopy as well as optical measurements to explain the physical processes behind the formation of the GaN nanomembranes. These novel nanomembranes, once transferred to other substrates, present a unique and technologically attractive path towards integrating high‐efficiency GaN optical components along with silicon electronics. Interestingly, due to their nanoscale thickness and macroscopic sizes, these nanomembranes may enable the production of flexible GaN‐based optoelectronics.     

Performance of Deep Ultraviolet GaN Avalanche Photodiodes Grown by MOCVD

We report high-performance GaN ultraviolet (UV) p-i-n avalanche photodiodes (APDs) fabricated on bulk GaN substrates. The fabricated GaN p-i-n diodes demonstrated optical gains > 10⁴ and low dark current densities operating at wavelengths from 280 to 360 nm. The result is among the highest III-N-based APD gains at the deep UV wavelength of 280 nm reported to date.     

P-type doping utilizing nitrogen and Mn doping of ZnO using MOCVD for ultraviolet lasers and spintronic applications

ZnO has distinct advantages over competing technologies such as GaN. Two advantages are the inherent improvement in ultraviolet (UV) brightness, necessary for the biological sensor application where the signal-to-noise ratio (SNR) is enhanced by a bright UV source, and the second is the availability of ZnO lattice-matched substrates, which will result in lower defect densities than GaN, higher manufacturing yield, and then lower cost. The ZnO material system’s advantage in exciton binding energy of 60 MeV, a three-time improvement over GaN, will result in UV emitters with superior performance.¹ An erratum to this article is available at .     

Enhanced carrier confinement in AlInGaN-InGaN quantum wells in near ultraviolet light-emitting diodes

To increase carrier confinement, the GaN barrier layer was substituted with an AlInGaN quaternary barrier layer which was lattice-matched to GaN in the GaN-InGaN multiple quantum wells (MQWs). Photoluminescence (PL) and high-resolution X-ray diffraction measurements showed that the AlInGaN barrier layer has a higher bandgap energy than the originally used GaN barrier layer. The PL intensity of the five periods of AlInGaN-InGaN MQWs was increased by three times compared to that of InGaN-GaN MQWs. The electroluminescence (EL) emission peak of AlInGaN-InGaN MQWs ultraviolet light-emitting diode (UV LED) was blue-shifted, compared to a GaN-InGaN MQWs UV LED and the integrated EL intensity of the AlInGaN-InGaN MQWs UV LED increased linearly up to 100 mA. These results indicated that the AlInGaN-InGaN MQWs UV LED has a stronger carrier confinement than a GaN-InGaN MQWs UV LED due to the larger barrier height of the AlInGaN barrier layer compared to a GaN barrier layer.     

Impact of UV/ozone surface treatment on AlGaN/GaN HEMTs

Surface treatment plays an important role in the process of making high performance AIGaN/GaN HEMTs. A clean surface is critical for enhancing device performance and long-term reliability. By experiment-ing with different surface treatment methods, we find that using UV/ozone treatment significantly influences the electrical properties of Ohmic contacts and Schottky contacts. According to these experimental phenomena and X-ray photoelectron spectroscopy surface analysis results, the effect of the UV/ozone treatment and the reason that it influences the Ohmic/Schottky contact characteristics of A1GaN/GaN HEMTs is investigated.     

GaN光电阴极测试与评估技术研究

GaN光电阴极的制备成功与否需用科学手段加以评估.在GaAs光电阴极多信息量测试系统的基础上,增设紫外光源,并对评估软件重新加以编写,设计出GaN光电阴极测试评估系统.利用该系统测试了GaN光电阴极在制备过程中的Cs源电流、O源电流、光电流和激活室真空度等多个信息量,并利用激活后的光谱响应对阴极进行了评估,实现了对GaN光电阴极性能的客观评价.     

Influence of GaN material characteristics on device performance for blue and ultraviolet light-emitting diodes

An analysis of blue and near-ultraviolet (UV) light-emitting diodes (LEDs) and material structures explores the dependence of device performance on material properties as measured by various analytical techniques. The method used for reducing dislocations in the epitaxial III-N films that is explored here is homoepitaxial growth on commercial hybride vapor-phase epitaxy (HVPE) GaN substrates. Blue and UV LED devices are demonstrated to offer superior performance when grown on GaN substrates as compared to the more conventional sapphire substrate. In particular, the optical analysis of the near-UV LEDs on GaN versus ones on sapphire show substantially higher light output over the entire current-injection regime and twice the internal quantum efficiency at low forward current. As the wavelength is further decreased to the deep-UV, the performance improvement of the homoepitaxially grown structure as compared to that grown on sapphire is enhanced.