高亮度GaN基蓝色LED的研究进展

超高亮度GaN基蓝色LED的发展将会引起照明技术的一场革命，它是目前全球半导体领域研究和投资的特点。本文综合分析了GaN材料的特性及相应的材料生长和欧姆接触、刻蚀工艺等关键技术，并对GaN基蓝色LED器件的进一步改进及应用前景作了展望。     

发展中的GaN微电子(一)

GaN微电子是继GaAs微电子之后在21世纪新发展起来微电子领域的国际战略制高点.从功率密度、高频性能、增强型器件与数字电路等方面阐述了GaN微电子最新的关键技术突破,并介绍了GaN微电子从UHF频段到3 mm波段在通讯、雷达和电子对抗等领域的应用研究进展.从GaN HEMT器件的电流崩塌、栅漏电流、逆压电效应、热电子...     

GaN技术发展新趋势

氮化镓(GaN)是第三代半导体的典型代表,受到学术界和产业界的广泛关注,正在成为未来超越摩尔定律所依靠的重要技术之一。对于射频(RF)GaN技术,在电信和国防两大主要应用增长行业,尤其是军用领域对先进雷达和通信系统不断增加的需求,推动了RF GaN器件向更高频率、更大功率和更高可靠性发展。文章梳理了在该领域中GaN RF/微波HEMT、毫米波晶体管和单片微波集成电路(MMIC)、GaN器件空间应用可靠性和抗辐射加固等技术发展的脉络。在功率电子方面,对高效、绿色和智能化能源的需求拉动GaN功率电子、电源变换器向快速充电、高效和小型化方向发展。简述了应用于纯电动与混合动力电动汽车(EV/HEV)、工业制造、电信基础设施等场合的GaN功率器件的研发进展和商用情况。在数字计算特别是量子计算前沿,GaN是具有应用前景的技术之一。介绍了GaN计算和低温电子技术研究的几个亮点。总而言之,对GaN技术发展几大领域发展的最新趋势作了概括性描述,勾画出技术发展的粗略线条。     

选择性生长技术制备GaN薄膜的研究进展

Ⅲ族氮化物化合物半导体GaN是目前半导体领域的研究热点之一,具有宽禁带、高温下物理、化学性质稳定等特点,在光电子、微电子等领域有广泛的应用.降低缺陷密度制备高质量的GaN外延层是生产高性能和高寿命GaN器件的关键,也是人们始终致力于研究的内容,本讨论对近年来发展的一种采用选择性生长技术生长GaN的方法、原理、进展情况进行了介绍.     

GaN和相关材料会议概况介绍

作为对GaN器件快速发展和商业化兴趣日益增浓的响应，1997年秋季在波士顿举行的材料研究协会GaN会议和相关材料专题讨论会的特点是首次讨论了氧化缘（GaN）二极管激光器的工业应用。日本东京日亚化学工业公司的S．Nakamura将开办一个讲习班，评述他的研究组在开创GaN激光器方面的发展，其中包括寿命超过100h的首支室温运转连续GaN激光器。继Nakamura之后三个发言人都来自非GaN界，他们将讨论GaN激光器在他们领域的市场机遇。他们也向参加讲习班的材料科学家和器件工程师阐述了这种激光器所需满足的规范。IBM公司的R．Melcher将讲述…     

晶圆级柔性高性能GaN HEMT及InP HBT器件

通过研究基于临时键合与解键合工艺的GaN、InP等材料无损剥离和晶圆级柔性集成等关键技术，提出了解决当前柔性化合物半导体器件普遍存在的转移后器件性能退化严重和大面积批量制造困难等问题的方案，制备出100 mm(4英寸)柔性GaN HEMT器件和75 mm (3英寸)InP HBT器件。其中，柔性GaN HEMT器件的饱和电流衰减仅为8.6%，柔性InP HBT器件的电流增益截止频率和最高振荡频率分别达到了358 GHz和530 GHz。表明采用本文介绍的柔性化方法制备的柔性电子器件在高频大功率等领域具有较好的应用前景。     

GaN器件在军事领域中的应用

GaN基半导体具有击穿电场强度高、饱和电子迁移率高、介电常数小、热导率大、抗辐射能力强等优点,广泛应用军用电子器件的制造。介绍了GaN器件在军事雷达、探测器以及激光引信等军事领域中的应用。     

北大成功研制出氮化镓基激光二极管

北京大学物理学院宽禁带半导体研究中心研制的氮化镓基激光二极管实现了电注入激射，激光波长405nm，峰宽0．12nm。这是继2004年7月该中心率先在国内获得光泵浦GaN基激光器受激发射之后所取得的又一突破。GaN基激光器是波长最短的半导体激光器．波长为405nm范围的蓝一紫光GaN基激光器是发展下一代大容量高密度光存储信息技术的关键性器件。在国防建设、生物、环境、照明、显示、打印和医疗等领域，也具有广阔的应用前景和巨大的市场需求。研制GaN基激光器是国家高科技攻关的重要项目之一。     

f_T/f_(max)>230/290GHZ的超薄势垒InAlGaN/AlN/GaN HEMTs

<正>氮化镓(GaN)材料具有大的禁带宽度、高击穿场强、高电子迁移率和高电子饱和速度等优良特性,不仅在微波大功率器件领域有广泛的应用,而且在超高频器件领域具备独特优势。南京电子器件研究所采用高极化强度的超薄InAlGaN势垒层形成InAlGaN/AlN/GaN异质结构,实现了电流截止     

化合物半导体器件与电路的研究进展

介绍了GaAs,InP和GaN等几种重要化合物半导体电子器件的特点、应用和发展前景。回顾了GaAs,InP和GaN材料的材料特性及其器件发展历程与现状。分别讨论了GaAs基HEMT由PHEMT渐变为MHEMT结构和性能的变化,GaAs基HBT在不同电路应用中器件的特性,InP基HEMT与HBT的器件结构及工作特性,GaN基HEMT与HBT的器件特性参数。总体而言,化合物半导体器件与电路在高功率和高频电子器件方面发展较快,GaAs,InP和GaN材料所制得的各种器件电路工作在不同的频率波段,其在相关领域发展潜力巨大。     

Ⅲ族氮化物基发光二极管制造工艺

Ⅲ族氮化物是近年来半导体发光器件研究领域中的热点。由于InN,GaN,AlN及由其组成的连续变化固溶体合金所构成的半导体微结构材料,具有宽禁带宽电子漂移饱和速度高、介电常数小及导热性能好等特点,使其在制作短波长、高亮度的发光器件方面具有极其光明的前景。本文系统介绍了以氮化镓为代表的Ⅲ族氮化物基发光二极管的制造工艺。从工作原理、材料生长、掺杂和欧姆接触等各方面,介绍了各种氮化物二极管的不同器件结构和制造工艺。在介绍国际上最新制造技术的同时,对其发展前景做出了展望。     

Application of metal halide perovskite photodetectors

In recent years,metal halide perovskite materials have attracted wide attention in the fields of photovoltaics(PVs),light-emitting diodes(LEDs)and photodetectors(PDs)due to their excellent light absorption[1-6],adjustable bandgaps and long carrier diffusion length.Compared with commercial Si and GaN photodetectors,perovskite photodetectors(PPDs)present wider light detection range,higher sensitivity and higher external quantum efficiency(EQE)[7-9].     

Cubic Phase GaN on Nano‐grooved Si (100) via Maskless Selective Area Epitaxy

A method of forming cubic phase (zinc blende) GaN (referred as c‐GaN) on a CMOS‐compatible on‐axis Si (100) substrate is reported. Conventional GaN materials are hexagonal phase (wurtzite) (referred as h‐GaN) and possess very high polarization fields (～MV/cm) along the common growth direction of <0001>. Such large polarization fields lead to undesired shifts (e.g., wavelength and current) in the performance of photonic and vertical transport electronic devices. The cubic phase of GaN materials is polarization‐free along the common growth direction of <001>, however, this phase is thermodynamically unstable, requiring low‐temperature deposition conditions and unconventional substrates (e.g., GaAs). Here, novel nano‐groove patterning and maskless selective area epitaxy processes are employed to integrate thermodynamically stable, stress‐free, and low‐defectivity c‐GaN on CMOS‐compatible on‐axis Si. These results suggest that epitaxial growth conditions and nano‐groove pattern parameters are critical to obtain such high quality c‐GaN. InGaN/GaN multi‐quantum‐well structures grown on c‐GaN/Si (100) show strong room temperature luminescence in the visible spectrum, promising visible emitter applications for this technology.     

Gallium-nitride-based materials for blue to ultravioletoptoelectronics devices

Breakthroughs in materials growth have enabled extremely high-efficiency blue and green GaN light emitting diodes (LEDs) to be achieved for the first time. Blue LEDs with external quantum efficiency exceeding 9% have enabled hybrid GaN/phosphor white lamp LEDs. GaN LEDs complete the primary color spectrum and have enabled bright and reliable full-color solid-state displays to be realized. Recently, room-temperature operation of continuous wave current-injection blue-violet lasers emitting at 417 nm has further increased the possible applications for GaN-based opto-electronic devices. In this paper, we review the key technologies for GaN-based materials and devices. Developments in the methods for thin-film deposition by metalorganic chemical vapor deposition and molecular beam epitaxy and resulting film properties are highlighted     

Prospects of gallium nitride double drift region mixed tunneling avalanche transit time diodes for operation in F, Y and THz bands

The potential of GaN as a wide band gap semiconductor is explored for application as double drift region mixed tunneling avalanche transit time (MITATT) diodes for operation at 120 GHz, 220 GHz and 0.35 THz using some computer simulation methods developed by our group. The salient features of our results have uncovered some peculiarities of the GaN based MITATT devices. An efficiency of more than 20% right up to a frequency of 0.35 THz (from the GaN MITATT diode) seems highly encouraging but a power output of only 0.76 W is indicative of its dismal fate. The existence of a noise measure minimum at the operating frequency of 0.35 THz is again exhilarating but the value of the minimum is miserably high i.e. more than 33 dB. Thus, although GaN is a wide band gap semiconductor, the disparate carrier velocities prevent its full potential from being exploited for application as MTATT diodes.     

GaN基和GaAs基半导体激光器的电学特性研究

介绍了一种能够全面表征半导体二极管器件的电学特性的方法,此方法结合半导体二极管的正向交流特性和直流特性,称之为正向交流小信号法。利用该方法深入地研究和对比分析了GaN基和GaAs基半导体激光器的电学特性,包括表观电容、串联电阻和理想因子。实验结果表明,对于GaN基和GaAs基半导体激光器,其开始发光的过程同步于其电容由正转变为负的过程。进一步实验结果表明,GaN基半导体激光器比GaAs基半导体激光器具有更大的串联电阻和更大的理想因子。这是由于GaN基激光器的器件工艺不够完善以及外延生长的GaN材料具有很大的位错密度。该研究为提高和改善GaN基激光器的性能提供了必要的依据以及理论指导。     

Potentials of GaP as millimeter wave IMPATT diode with reference to Si, GaAs and GaN

This paper presents the simulation results of DC,small-signal and noise properties of GaP based Double Drift Region( DDR) Impact Avalanche Transit Time( IMPATT) diodes. In simulation study we have considered the flat DDR structures of IMPATT diode based on GaP,GaAs,Si and GaN( wurtzite,wz) material. The diodes are designed to operate at the millimeter window frequencies of 94 GHz and 220 GHz. The simulation results of these diodes reveal GaP is a promising material for IMPATT applications based on DDR structure with high break down voltage( V_B) as compared to Si and GaAs IMPATTs. It is also encouraging to worth note GaP base IMPATT diode shows a better output power density of 4. 9 × 10~9 W/m~2 as compared to Si and GaAs based IMPATT diode. But IMPATT diode based on GaN( wz) displays large values of break down voltage,efficiency and power density as compared to Si,GaAs and GaP IMPATTs.     

Graphene‐Assisted Epitaxy of Nitrogen Lattice Polarity GaN Films on Non‐Polar Sapphire Substrates for Green Light Emitting Diodes

Lattice polarity is a key point for hexagonal semiconductors such as GaN. Unfortunately, only Ga‐polarity GaN have been achieved on graphene till now. Here, the epitaxy of high quality nitrogen‐polarity GaN films on transferred graphene on non‐polar sapphire substrates by molecular beam epitaxy is reported. This success is achieved through atomic nitrogen irradiation, where C? N bonds are formed in graphene and provide nucleation sites for GaN and leading to N‐polarity GaN epitaxy. The N‐polarity characteristics are confirmed by chemical etching and transmission electron microscopy measurement. Due to the higher growth temperature of InGaN at N‐polarity than that at Ga‐polarity, green light emitting diodes are fabricated on the graphene‐assisted substrate, where a large redshift of emission wavelength is observed. These results open a new avenue for the polarity modulation of III‐nitride films based on 2D materials, and also pave the way for potential application in longer wavelength light emitting devices.     

Enhanced functionality in GaN and SiC devices by using novel processing

Some examples of recent advances in enhancing or adding functionality to GaN and SiC devices through the use of novel processing techniques are discussed. The first example is the use of ion implantation to incorporate transition metals such as Mn, Cr and Co at atomic percent levels in the wide bandgap semiconductors to produce room temperature ferromagnetism. A discussion is given of the phase space within which single-phase material can be obtained and the requirements for demonstrating the presence of a true dilute magnetic semiconductor. The ability to make GaN and SiC ferromagnetic leads to the possibility of magnetic devices with gain, spin FETs operating at low voltages and spin polarized light emitters. The second example is the use of novel oxides such as Sc₂O₃ and MgO as gate dielectrics or surface passivants on GaN. True inversion behavior has been demonstrated in gated MOS-GaN diodes with implanted n-regions supplying the minority carriers need for inversion. These oxide layers also effectively mitigate current collapse in AlGaN/GaN HEMTs through their passivation of surface states in the gate–drain region. The third example is the use of laser drilling to make through-wafer via holes in SiC, sapphire and GaN. The ablation rate is sufficiently high that this maskless, serial process appears capable of achieving similar throughput to the more conventional approach of plasma etching of vias. The fourth example is the use of either ungated AlGaN/GaN HEMTs or simple GaN and SiC Schottky diodes as sensors for chemicals, biogens, radiation, combustion gases or strain. The sensitivity of either the channel carrier density or the barrier height to changes in surface condition make these materials systems ideal for compact robust sensors capable of operating at elevated temperatures.     

美、日、欧宽带隙半导体技术发展研究

美国、日本和欧盟等国在SiC、GaN和金刚石等宽带隙半导体器件与电路研究中已取得多项里程碑性的进展,这些飞速发展已经证实宽带隙半导体是当之无愧的新一代半导体材料,并将替代Si和GaAs应用于相控阵雷达、高保密通信及其他重要设施等诸多国防和航空领域.概述了SiC和GaN等宽带隙半导体在军事、宇航及其他恶劣环境应用中优于Si和GaAs等传统半导体技术的具体体现.介绍了美国、日本和欧盟在发展宽带隙半导体技术上的重大举措及其在器件开发与研究中的最新进展.着重探讨了美、日、欧等发达国家实施的宽带隙半导体技术发展计划及其对其军事、航天及其他重要设施产生的深远影响.