退火参数对p型GaAs欧姆接触性能的影响

采用磁控溅射的方法在p型GaAs衬底上沉积了Ti/Pt/Au金属薄膜,研究了退火工艺参数(温度和时间)对p-GaAs/Ti/Pt/Au欧姆接触性能的影响。结果表明:p-GaAs上制作的Ti/Pt/Au金属系统能在很短的退火时间(60 s)内形成很好的欧姆接触。过分延长退火时间,并不能改善系统的欧姆接触性能。退火温度在400~450℃时均可得到较好的欧姆接触。当退火温度为420℃,退火时间为120 s时,比接触电阻率达到最低,为1.41×10–6.cm2。     

p型GaAs欧姆接触性能研究

为了研究半导体光电器件p-GaAs欧姆接触的特性,利用磁控溅射在p-GaAs上生长Ti厚度在10~50 nm范围、Pt厚度在30~60 nm范围的Ti/Pt/200 nm Au电极结构。利用传输线模型测量了具有不同的Ti、Pt厚度的Ti/Pt/200 nm Au电极结构接触电阻率,研究了退火参数对欧姆接触性能的影响,同时分析了过高温度导致电极金属从边缘向内部皱缩的机理。结果表明,Ti厚度为30 nm左右时接触电阻率最低,接触电阻率随着Pt厚度的增加而增加;欧姆接触质量对退火温度更敏感,退火温度达到510 ℃时电极金属从边缘向内部皱缩。采用40 nm Ti/40 nm Pt/200 nm Au作为半导体光电器件p-GaAs电极结构,合金条件为420 ℃,30 s可以形成更好的欧姆接触。     

Ti/Al/Ti/Au与AlGaN欧姆接触特性

研究了溅射Ti/Al/Ti/Au四层复合金属与AlGaN/GaN的欧姆接触特性,并就环境温度对欧姆接触特性的影响进行了分析研究.试验证实:溅射的Ti/Al/Ti/Au与载流子浓度为2.24×1018cm-3的AlGaN之间在室温下无需退火即可形成欧姆接触.随快速退火温度的升高接触电阻降低.快速退火时间30s已可实现该温度下最佳欧姆接触.当工作温度不高于300℃时接触电阻几乎不受温度的影响.     

Ti/Al/Ti/Au与AlGaN欧姆接触特性

研究了溅射 Ti/ Al/ Ti/ Au四层复合金属与 Al Ga N / Ga N的欧姆接触特性 ,并就环境温度对欧姆接触特性的影响进行了分析研究 .试验证实 :溅射的 Ti/ Al/ Ti/ Au与载流子浓度为 2 .2 4× 10 1 8cm- 3的 Al Ga N之间在室温下无需退火即可形成欧姆接触 .随快速退火温度的升高接触电阻降低 .快速退火时间 30 s已可实现该温度下最佳欧姆接触 .当工作温度不高于 30 0℃时接触电阻几乎不受温度的影响     

n型4H-SiC上Ni/Pt和Ti/Pt欧姆接触(英文)

研究了Ni/Pt和Ti/Pt金属在n型4H-SiC上的欧姆接触。在1 020℃退火后,Ni/Pt与n型4H-SiC欧姆接触的比接触电阻为2.2×10-6Ω·cm2。Ti/Pt与n型4H-SiC欧姆接触的比接触电阻为5.4×10-6Ω·cm2,退火温度为1 050℃。虽然Ni的功函数比Ti的功函数高,但是Ni比Ti更容易与n型4H-SiC形成欧姆接触。使用能谱分析仪(EDX)分析了Ni/Pt和Ti/Pt金属与4HSiC接触面的元素,观察到C原子相对于Pt原子的原子数分数随退火温度的变化而不同。实验验证了在n型4H-SiC中退火导致的碳空位起施主作用是有利于欧姆接触形成的主要原因。     

InAs/AlSb异质结的Pd/Ti/Pt/Au合金化欧姆接触

为了得到较低的接触电阻, 研究了帽层未掺杂的InAs/AlSb异质结的Pd/Ti/Pt/Au合金化欧姆接触.利用传输线模型 (TLM) 测量了接触电阻Rc.在最佳的快速热退火条件为275℃和20s时, InAs/AlSb异质结的Pd/Ti/Pt/Au接触电阻值为0.128Ω·mm.TEM观察发现经过快速热退火后Pd已经扩散到半导体中有利于高质量欧姆接触的形成.研究表明经过Pd/Ti/Pt/Au合金化欧姆接触后Rc有明显减小, 适用于InAs/AlSb异质结的应用.     

金属/n型AlGaN欧姆接触

用传输线模型对n型AlGaN(n-AlGaN)上Au/Pt/Al/Ti多金属层欧姆接触进行了接触电阻率的测量.在850℃退火5min后,测得欧姆接触电阻率达1.6×10-4Ω·cm2.经X射线衍射分析,Au/Pt/Al/Ti/n-AlGaN界面固相反应得出在500℃以上退火过程中,AlGaN层中N原子向外扩散,在AlGaN表面附近形成n型重掺杂层,导致欧姆接触电阻率下降;随退火温度的升高,N原子外扩散加剧,到800℃以上退火在Au/Pt/Al/Ti/n-AlGaN界面形成Ti2N相,导致欧姆接触电阻率进一步下降.     

金属/n型AlGaN欧姆接触

用传输线模型对n型AlGaN(n-AlGaN)上Au/Pt/Al/Ti多金属层欧姆接触进行了接触电阻率的测量.在850℃退火5min后,测得欧姆接触电阻率达1.6×10-4Ω·cm2.经X射线衍射分析,Au/Pt/Al/Ti/n-AlGaN界面固相反应得出在500℃以上退火过程中,AlGaN层中N原子向外扩散,在AlGaN表面附近形成n型重掺杂层,导致欧姆接触电阻率下降;随退火温度的升高,N原子外扩散加剧,到800℃以上退火在Au/Pt/Al/Ti/n-AlGaN界面形成Ti2N相,导致欧姆接触电阻率进一步下降.     

Ti/Al/Ni/Au金属体系在N-polar GaN上的欧姆接触特性

利用金属有机化合物化学气相淀积(MOCVD)在SiC衬底上外延生长了N-polar GaN材料,采用传输线模型(TLM)分析了Ti/Al/Ni/Au金属体系在N-polar GaN上的欧姆接触特性.结果表明,Ti/Al/Ni/Au (20/60/10/50 nm)在N-polar GaN上可形成比接触电阻率为2.2×10-3Ω·cm2的非合金欧姆接触,当退火温度升至200℃,比接触电阻率降为1.44×10-3 Ω·cm2,随着退火温度的进一步上升,Ga原子外逸导致欧姆接触退化为肖特基接触.     

AlGaN/GaN异质结构的欧姆接触

通过改变Ti/Al的结构及退火条件,研究了AlGaN/GaN异质结构上Ti/Al/Ni/Au金属体系所形成的欧姆接触.结果表明,Ti/Al/Ni/Au金属厚度分别为20,120,55和45nm,退火条件为高纯N2气氛中850℃、30s时在AlGaN/GaN异质结构上获得了良好的欧姆接触,其比接触电阻率为3.30×10-6Ω·cm2.SEM分析表明该条件下的欧姆接触具有良好的表面形貌,可以很好地满足高性能AlGaN/GaN高电子迁移率晶体管制造的要求.     

P型GaAs欧姆接触的制作

在以Be作为离子源离子注入形成的P型GaAs衬底上分别使用Ti/Pt/Au和Cr/Pt/Au多层金属作为欧姆接触金属,并对比合金前后的差别。结果表明,使用Ti/Pt/Au作为欧姆接触金属效果更好,合金对于降低欧姆接触电阻率效果明显,合金后Ti/Pt/Au的接触电阻率可达到3.08×10-5Ω.cm2。     

The thermal stability of ohmic contact to n-type InGaAs layer

The thermal stability of ohmic contact to n-type InGaAs layer is investigated. When Ni/Ge/Au is used as the contact metal, the characteristics of the ohmic contact are degraded after thermal treatment. The specific contact resistance of (Ni/Ge/Au)-InGaAs ohmic contact after annealing at 450°C is about 15 times larger than that of as-deposited sample. This is due to the decomposition of InGaAs and the interdiffusion of Ga and Au. A new phase of Au₄ln appears after annealing at 300°C. While in the case of Ti/Pt/Au, Au does not penetrate into the InGaAs layer as revealed by secondary ion mass spectroscopy. The specific contact resistance of (Ti/Pt/Au)-InGaAs ohmic contact after annealing at 450°C is eight times larger than that of as-deposited sample. Therefore, the thermal stability of (Ti/Pt/Au)-InGaAs ohmic contact is better than that of (Ni/Ge/Au)InGaAs ohmic contact.     

垂直结构GaN基LED用Ni/Ag反射镜电极

Ni/Ag/Ti/Au金属系反射镜电极广泛用于GaN基垂直结构发光二极管(LED)的传统制造工艺.这种电极需要进行高温长时间整体退火才能获得高质量的欧姆接触,但对电极的反射率和器件性能影响较大.介绍了一种新工艺方法,该方法将电极分解为接触层和反射层,降低反射层经历的退火温度和时间,获得了拥有良好的欧姆接触特性和高反射率的反射镜电极,解决了传统电极光学性能和电学性能相互制约的问题.首先生长极薄的Ni/Ag作为接触层,对接触层进行高温长时间退火后再生长厚层Ag作为反射层,之后再进行一次低温退火.使得对反射起主要作用的反射层免于高温长时间退火,相较于传统Ni/Ag/Ti/Au电极,该方法在获得更优良的欧姆接触的同时,提升了电极的反射率.在氧气氛围下进行500℃接触层退火3 min,400℃整体退火1 min后,电极的比接触电阻率为1.7×l0-3Ω·cm2,同时在450 nm处反射率为93％.     

Effect of Pt barrier on thermal stability of Ti/Al/Pt/Au in ohmic contact with Si-implanted n-type GaN layers

We report the effect of the Pt barrier on the thermal stability of Ti/Al/Pt/Au in ohmic contact with Si-implanted n-type GaN layers. Ti/Al/Au (25/100/200 nm) and Ti/Al/Pt/Au (25/100/50/200 nm) multilayers were, respectively, deposited on as-implanted and recovered Si-implanted n-type GaN samples. The associated dependence of the specific contact resistance on the annealing time at various temperatures was compared. The long-term ohmic stability of a Ti/Al/Pt/Au multilayer in contact with a Si-implanted n-type GaN layer was much better than that of the Ti/Al/Au multilayer. This superior stability is attributed to the barrier function of the Pt interlayer. The Pt/Au bilayer can also passivate the propensity of oxidation for the conventional Ti/Al bilayer in contact with n-type GaN layers at elevated temperatures.     

用于紫外探测器的AlGaN/GaN异质结构的Ti/Al/Ni/Au欧姆接触特性

采用Ti/Al/Ni/Au多层金属体系在Al0.27Ga0.73N/GaN异质结构上制备了欧姆接触.分别采用线性传输线方法(LTLM)和圆形传输线方法(CTLM)对其电阻率进行了测试.当Ti(10nm)/Al(100nm)/Ni(40nm)/Au(100nm)金属体系在650℃高纯N2气氛中退火30s时,测量得到的最小比接触电阻率为1.46×10-5Ω·cm2.并制备了Al0.27Ga0.73N/GaN光导型紫外探测器,通过测试发现探测器的暗电流.电压曲线呈线性分布.实验结果表明在Al0.27 Ga0.73N/GaN异质结构上获得了好的欧姆接触,能够满足制备高性能AlGaN/GaN紫外探测器的要求.     

多层金属-n型4H-SiC的欧姆接触

研究了热退火条件下Au/Ti/Ni-4H-SiC欧姆接触形成机制.通过950 ℃下的快速热退火形成的最低欧姆接触电阻为2.765×10-6 Ω·cm2.SIMS分析表明退火过程中NiSi化合物的形成会带来SiC内部多余C原子的溢出,并在接触面上与Ti形成间隙化合物TiC.这一过程造成接触表面存在由大量C空位形成的缺陷层从而增强了表面间接隧穿.通过界面能带结构图直观地解释了欧姆接触在热退火条件下的形成机制.     

台面型InP/InGaAs PIN光伏探测器的p-InP低阻欧姆接触

研究了电子束蒸发淀积的非合金膜系Au/Pt/Ti/p-InP(2×1018cm-3)接触的物理特性,通过450℃、4 min的快速退火,获得了欧姆接触,其比接触电阻为7.3×10-5 Wcm2.接触电极退火后,采用离子溅射法淀积加厚电极Cr/Au.利用俄歇电子能谱(AES)进行深度剖面分析,表明Pt层能够相对有效地阻挡...     

Au and non-Au based rare earth metal-silicide ohmic contacts to p-InGaAs

The aim of this study is to improve the electrical properties of ohmic contacts that plays crucial role on the performance of optoelectronic devices such as laser diodes (LDs), light emitting diodes (LEDs) and photodetectors (PDs). The conventional (Pd/Ir/Au, Ti/Pt/Au and Pt/Ti/Pt/Au), Au and non-Au based rare earth metal-silicide ohmic contacts (Gd/Si/Ti/Au, Gd/Si/Pt/Au and Gd/Si/Pt) to p-InGaAs were investigated and compared each other. To calculate the specific contact resistivities the Transmission Line Model (TLM) was used. Minimum specific contact resistivity of the conventional contacts was found as 0.111 × 10⁻⁶ Ω cm² for Pt/Ti/Pt/Au contact at 400 °C annealing temperature. For the rare earth metal-silicide ohmic contacts, the non-Au based Gd/Si/Pt has the minimum value of 4.410 × 10⁻⁶ Ω cm² at 300 °C annealing temperature. As a result, non-Au based Gd/Si/Pt contact shows the best ohmic contact behavior at a relatively low annealing temperature among the rare earth metal-silicide ohmic contacts. Although the Au based conventional ohmic contacts are thermally stable and have lower noise in electronic circuits, by using the non-Au based rare earth metal-silicide ohmic contacts may overcome the problems of Au-based ohmic contacts such as higher cost, poorer reliability, weaker thermal stability, and the device degradation due to relatively higher alloying temperatures. To the best of our knowledge, the Au and non-Au based rare earth metal-silicide (GdSi_x) ohmic contacts to p-InGaAs have been proposed for the first time.     

非故意掺杂GaN上Ti/Al/Ni/Au欧姆接触研究

基于圆形传输线模型,研究了背景载流子浓度为71016cm3的非故意掺杂GaN与Ti/Al/Ni/Au多层金属之间欧姆接触的形成。样品在N2气氛中,分别经过温度450,550,700,800,900℃的1 min快速热退火处理后发现,当退火温度高于700℃欧姆接触开始形成,随着温度升高欧姆接触电阻持续下降,在900℃时获得了最低比接触电阻6.6106O·cm2。研究表明,要获得低的欧姆接触电阻,需要Al与Ti发生充分固相反应,并穿透Ti层到达GaN表面;同时,GaN中N外扩散到金属中,在GaN表面产生N空位起施主作用,可提高界面掺杂浓度,从而有助于电子隧穿界面而形成良好欧姆接触。