一种新型全方位反射AlGaInP薄膜发光二极管

提出了一种新型全方位反射A1GalnP LED结构和制作工艺.GaAs外延片与含导电孔的SiO2,Au形成全方位反射镜后,银浆键合在Si支架上,去除GaAs衬底,制作薄AuGeNi电极,粗化,生长ITO,制作厚AuGeNi电极,合金则形成ODR薄膜LED结构.300μm×300μm管芯裸装在TO-18金属管座上,在20mA的电流驱动下,测得电压为2.2V,光强达到195mcd,光功率达到3.78mW,比常规吸收衬底LED提高3.6倍.     

GaAs/Ge太阳能电池电极银镀层结合力的研究

采用自制的LP-MOCVD设备,在Ge衬底外延生长出GaAs电池结构,并对电池结构片进行了后工艺制作,同时对电极制作中银镀层结合力的影响因素进行了研究。研究结果表明选择带电入池,无冲击电流方式时,可增强银镀层的结合力。同时采用扫描电子显微镜(SEM)和电子微探针对n型Ge衬底上AuGeNi背电极不同层面的成分进行了分析测试,测试数据表明钨污染将会使银镀层结合力变差。     

LED阵列的设计和制作工艺研究

根据Al GaInP外延片的结构特点设计了LED型微显示器件的主要结构。利用Markus-Christian Amann等人提出的模型对器件电流注入后的空间分布进行了简单的理论分析,总结出了像素元和上隔离沟槽的理想尺寸分别是16μm×16μm和2μm。简述了减薄GaAs衬底的作用,设计衬底电隔离沟槽宽度为5μm。采用湿法腐蚀工艺进行器件结构制备,利用不同的腐蚀剂对金属层、p-GaP层、Al GaInP层和n-GaAs衬底层进行腐蚀。实验结果表明,腐蚀后的沟槽形貌较好,其深度和宽度可以达到设计要求。     

基于HgCdTe薄膜和GaAs／AlGaAs多量子阱的红外光电探测器列阵

俄罗斯科学院西伯利亚分院半导体物理研究所设计并制作了若干用于3μm～12μm光谱范围的光电探测器组件.这些光电探测器组件都是以用分子束外延方法生长的Hg1-xCdxTe/GaAs异质结构和GaAs/AlGaAs多量子阱结构为基础的,其HgCdTe光敏层长在带CdZnTe中间缓冲层的GaAs衬底上.为了减少表面对复合过程的影响,生长了增加表面组分的渐变带隙HgCdTe层.     

硅衬底上制作GaAs两层器件

<正> 据报道日本冲电气在 Si 衬底上直接形成可制作器件的 GaAs,继而完成 GaAs 三维电路元件。Si 衬底上的 GaAs 晶体由 MOCVD 法生成,用直接离子注入法,最终制成17级 E/D 结构的环形振荡器。栅长1μm,栅宽10μm 的典型器件的跨导为240mS/mm,环形振荡器的 t_(pd)是51ps/门,t_(ps)·p 是10.4,fJ/门(t_(pd)为63ps/门),这些数值几乎与平常的 GaAs 器件一样。     

高温AlGaInP/GaAs双异质结双极晶体管

利用Mo/W/Ti/Au难熔金属作为发射极欧姆接触设计并制作了一种用于功率放大器的新结构AlGaInP/GaAs双异质结双极晶体管(DHBT),分析了与传统AuGeNi作为接触电极的AlGaInP/GaAs DHBT的直流特性差异.研究结果表明,利用难熔金属作为欧姆接触电极的DHBT器件具有较好的高温特性,并进一步分析了其具有良好高温特性的机理.     

Ga_(1-x)Al_xAs-GaAs DH 激光器的质子轰击研究

质子轰击条形DH激光器,通常我们采用常规的液相外延方法来制造。一般在n-GaAs衬底材料上生长Ga_(1-x)Al_xAs-GaAs五层DH结构。n面衬底上的接触电极用AuGeNi合金化形成;p-GaAs顶层上则先扩散锌,蒸发Cr-Au。对质子束的掩蔽     

宽带3-5μm量子阱红外探测器的研制

采用分子束外延方法在GaAs衬底上生长了n型掺杂的应变InGaAs/A1GaAs多量子阱结构,制作成3-5μm波段的量子阱红外探测器,响应峰值波长λp=4.2μm,响应带宽可达△λ/λ=50%,500K黑体探测率DBB(500,1000,1)达1.7×1010cm@Hz1/2/W.     

在Si上集成GaAs LED

美国TI公司中央研究实验室研制成功一种在Si3位CMOS译码器上集成8只GaAs LED阵列.电源电压5V.Si衬底材料为P~-.该实验室采用了如下工艺:(1)先生长CMOS源和漏,然后通过SUi_2/Si_3N_4制作n~+Si,然后再在n~+Si飞上集成GaAs LED;(2)清洗工艺采用H_2SO_4-H_2O_2+2%HF;(3)用常规两步MDE方法生长1.5μmGaAs缓冲层.然后再生长GaAs双异质结LED外延层.     

无掩模Si圆柱纳米图形衬底上GaAs的异变外延生长

采用金属有机化学气相沉积方法在无掩模的直径为400nm的圆柱Si(100)图形衬底上外延生长了GaAs薄膜。图形衬底采用纳米压印技术及反应离子刻蚀技术制作而成。运用两步法生长工艺在此图形衬底上制备了厚度为1.8μm的GaAs外延层。GaAs的晶体质量通过腐蚀坑密度和透射电镜表征。图形衬底上的GaAs外延层表面腐蚀坑密度约1×107 cm-2,比平面衬底上降低了两个数量级。透射电镜观测显示大部分产生于GaAs/Si异质界面的穿透位错被阻挡在圆柱顶部附近。     

`Flip-chip' transfer of ZnSSe/ZnSe/CdZnSe LED films

A ZnSSe/ZnSe/CdZnSe light-emitting diode (LED) film grown on GaAs by molecular beam epitaxy (MBE) has been successfully transferred from a GaAs substrate to a silicon substrate by combining both mechanical polishing and chemical wet etching techniques. The external quantum efficiency of the LED was enhanced by more than a factor of 2 via insertion of a reflector layer beneath the device structure. The device can be implemented in hybrid quasimonolithic integration. Technology applications include fabrication of LEDs with enhanced external quantum efficiency and II-VI surface emitting lasers     

基于Au/Au直接键合的高亮度ODRLED

提出利用Au/Au直接键合制作高亮度全方位反光镜(ODR)LED的新工艺。工艺采用Si做转移衬底,氧化铟锡(ITO)做窗口层和缓冲层,在0.35mPa压力,260°C的低温下实现Au/Au固相直接键合。直接键合后,Al-GaInP有源区与Si衬底结合牢固完整,保证了全方位反光镜的性能。在正向电流20mA下,键合ODR结构LED的正向压降是常规吸收衬底LED的80%,光输出功率和流明效率是常规吸收衬底LED的1.5倍和2.1倍。     

AlGaInP-sapphire glue bonded light-emitting diodes

A novel method was proposed to glue an AlGaInP-GaAs light-emitting diode (LED) onto a transparent sapphire substrate. The absorbing GaAs was subsequently removed by selective wet etching. It was found that the emission efficiency could reach 401 m/W under 20-mA current injection for the 622-nm glue bonded (GB) AlGaInP-sapphire LED. It was also found that these GB LEDs are highly reliable, with small variations in operation voltage and luminescence intensity during the life test.     

Transferring of GaAs microtips using selective wet etching Al0.7Ga0.3As sacrificial layer

GaAs pyramidal microtips were successfully transferred from GaAs substrate to target wafer by a simple technique, i.e., selective wet etching off AlGaAs sacrificial layer. A GaAs/Al_0.7Ga_0.3As/GaAs sandwich structure is firstly formed on GaAs (0 0 1) substrate by metalorganic chemical vapor deposition, and then GaAs pyramidal microtips are grown on the sandwich structure using selective liquid-phase epitaxy. The GaAs microtips are removed from the sandwich structure by selective wet etching Al_0.7Ga_0.3As layer using concentrated HCl solution. Finally, the tips are glued onto the target wafer by a negative photoresist. During this transfer process the tips are completely encapsulated in a positive photoresist to protect against attack. Scanning electron microscopy images show that GaAs tips can be successfully transferred without any damage by this technique. The achievement reported here represents a significant step towards the application of scanning near-field optical microscopy.     

GaAs PHEMT栅选择腐蚀工艺研究

基于GaAs PHEMT(赝配高电子迁移率晶体管)材料结构的设计,材料生长过程中增加了一层腐蚀终止层。经过大量的实验和腐蚀液体系的选取,完成了GaAs PHEMT工艺中能用于大批量生产的栅加工工艺。利用选择腐蚀终止层可以很容易地达到夹断电压和漏极电流的批量生产的一致性。本研究利用磷酸腐蚀液体系,在材料的设计中增加了InxGa1-xP腐蚀终止层,结果达到了预期目的,并已用于GaAs 0.25μm PHEMT标准工艺的生产中,获得了良好的经济效益。     

光泵浦垂直外腔面发射激光器斜率效率的分析

研究了光泵浦垂直外腔面发射激光器(OPS-VECSEL)的湿法腐蚀工艺,采用快速腐蚀和精细选择腐蚀相结合的腐蚀方法,使得衬底能被干净地腐蚀掉,并精确停留在阻挡层,得到高平整度的外延片表面,提高了泵浦效率,降低了散射损耗。从理论上分析了外延片表面粗糙度与OPS-VECSEL斜率效率的关系,得出如果在外延片上镀一层λ/4单介质增透膜,能进一步提高VECSEL的斜率效率。     

液相外延生长GaAs微探尖刻蚀剥离技术研究

介绍一种用于扫描近场光学显微术(NSOM)传感头的GaAs微探尖的生长剥离技术.通过SiO2掩膜窗口,利用一次选择液相外延制备周期性阵列的GaA微探尖.在GaAs衬底与GaAs微探尖之间引入AlGaAs层,并对窗口大小的AlGaAs层进行选择腐蚀,将单个GaAs微探尖从GaAs衬底上剥离下来.扫描电子显微镜显示的结果表明,此微探尖具有金字塔结构、表面光滑凡转移过程无损伤.这种技术制备的GaAs微探尖的形貌与质量主要由晶体的结构决定,具有可重复,表面光滑、适合批量生产的优点.     

High Light-Extraction GaN-Based Vertical LEDs With Double Diffuse Surfaces

High light-extraction (external quantum efficiency ~40%) 465-nm GaN-based vertical light-emitting diodes (LEDs) employing double diffuse surfaces were fabricated. This novel LED structure includes one top transmitted diffuse surface and another diffuse omnidirectional reflector (ODR) on the bottom of a LED chip. The diffusive ODR consists of a roughened p-type GaN layer, an indium-tin-oxide (ITO) low refractive index layer, and an Al layer. The surface of the p-type GaN-layer was naturally roughened while decreasing the growth temperature to 800 degC. After flip-bonding onto a Si substrate by AuSn eutectic metal and laser lift-off processes to remove the sapphire substrate, an anisotropic etching by dilute potassium hydroxide (KOH) was employed on the N-face n-GaN layer to obtain transmitted diffuse surfaces with hexagonal-cone morphology. The double diffused surfaces LEDs show an enhancement of 56% and 236% in light output power compared to single side diffused surface and conventional LEDs, respectively. The devices also show a low leakage current in the order of magnitude of 10 ^-8 A at -5 V and a calculated external quantum efficiency of about 40%. The high scattering efficiency of double diffused surfaces could be responsible for the enhancement in the device light output power     

Thin MBE GaAs millimetre-wave mixer diode using Ge substrate

Thin substrateless MBE GaAs diodes have been processed for mixer applications. MBE growth of an inverted n/n+ GaAs structure on Ge was achieved. The Ge substrate was removed by preferential etching. A noise figure of less than 6.0 dB at 94 GHz was obtained.     

Fabrication process simulation and reliability improvement of high-brightness LEDs

To enhance the light extraction efficiency and thermal performance of AlGaInP light-emitting diodes (LEDs), the wafer bonding technique which can replace the GaAs substrate with other high thermal conductivity substrates was applied. However, this technique may make the film crack during either the removal etching process of the GaAs substrate or the annealing process after the GaAs removal. Therefore, this crack problem is an important issue in the reliability/yield of high-brightness LEDs. In this research, a detailed finite element model of the high-brightness AlGaInP LED, which is replaced by the GaAs substrate with high thermal conductivity substrate through the Au–In metal bonding technique, was developed and fabricated. In addition, the mechanical behavior of wafer-level metal bonding was also simulated by finite element analysis (FEA) and validated by experimental measurements. Hence, the above validated simulation technique combined with process modeling is used to understand the stress variation of the multilayer structure of AlGaInP LED during the fabrication process and to find the principal cause of the film crack.