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Study OF Ultra-High Speed Heterojunction Bipolar Transistors with a Heavily Carbon-Doped Base

重碳掺杂基极超高速异质结双极晶体管的研究

基本信息

批准号：
04555066
负责人：
KONAGAI Makoto
金额：
$ 11.65万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04555066/
关键词：
MOMBE Carbon Carbon-doped baes HBT Heavy doping InGaP Tertiarybutylphosphine GaAs HBT InP InGaAs HBT 超高濃度ドーピング GaAs InGaAs ターシャリブチルフォスフィン HBT トリメチルガリウムネオペンタン

项目摘要

Heterojunction bipolar transistors (HBTs) have attracted much attention as high-speed devices. In this research, it was strongly proposed that for further improved device performance of HBTs, reduction of base resistance is greatly important. In other words, heavily doped base layr with the well-confined base dopant is one of key structural parameters for realizing high-speed HBTs.From these points, effects of reduced base resistance on static and dynamic characteristics of InGaP/GaAs HBTs with an ultra-high doped base were studied by solving the basic device equations and the hybrid-pi type equivalent circuit model. By increasing the base hole concentration to 1.5x10^<21>cm^<-3>, current gains were estimated to be over 10 by assuming the minority carrier lifetime gamma_n of 10-100ps, and current-gain cutoff frequency f_T of 110 GHz and maximum oscillation frequency f_<max> of 160 GHz were predicted. Switching characteristics were also studied by using a SPICE simulator, and propagatio … More n delay time t_<pd> of l ps/gate was achieved in that device structures.Based on this consideration, heavy impurity-doping technique is developed by using novel crystal growth technique : metalorganic molecular beam epitaxy (MOMBE) . Instead of conventional p-type dopants such as beryllium (Be) and zinc (Zn) for base layr in HBTs, carbon (C) is proposed as a novel base dopant because of excellent stability and capability of heavy doping. Heavily carbon-doped p-type GaAs and InGaAs were developed as base materials by MOMBE with trimethylgallium (TMG) , and carbon-doping characteristics and electrical, optical and structural properties were studied in detail. Furthermore, phosphide materials such as InGaP and InP are also proposed in this research as novel emitter materials of the HBTs because of the tendency of low surface recombination velocity, and MOMBE growth of these compounds is investigated with new metalorganic phosphorus precursor : tertiarybutylphosphine (TBP) .In the growth of high quality materials, the catalysis by means of heated tantalum (Ta) inside the cracking cell was important to effectively decompose the TBP as compared to simple pyrolysis. Controllability of Si-doping in In_<0.5>Ga_<0.5>P suitable for HBT application was also studied by using cracked Si_2H_6. In the growth of InP by MOMBE with TBP,it was revealed that carbon from the TBP is incorporated and acts as well-activated donor.By combining these MOMBE growth techniques, InP/InGaAs HBTs with carbon-doped n-type InP emitter and carbon-doped p-type InGaAs base are proposed and fabricated for the first time in the world. In common-emitter static characteristics, relatively large commonemitter breakdown voltage BV_<CEO>above 6 V was achieved, and small signal current gain h_<fe> of 20 and d.c.current gain h_<FE> of 11 were obtained at collector current density J_C of 0.15kA/cm^2 for a device with emitter area A_E of 80*80mum^2.Furthermore, InGaP/GaAs HBTs having an ultrahigh carbon-doped base with a hole concentration of the order of 10^<21>cm^<-3> are realized for the first time. By using that device structure, improved high-frequency performance is strongly expected because base resistance could be extremely decreased due to the ultra-high doping in the base. In fact, h_<fe> of 16 and h_<FE> of 12 were obtained for devices with a base thickness of 15 nm. In the reliability measurements, a significant degradation of current gain was not observed in the range investigated, indicating a perfect stability of carbon as a p-type dopant. In conclusions, successful realization of HBTs with unique original structures ; Inp/InGaAs HBTs with carbon-doped InP emitter and carbondoped InGaAs base and InGap/GaAs HBTs with an ultra-high carbon-doped base (p=1.5*10^<21>cm^<-3>) , was studied for the first time. Less

异质结双极型晶体管（HBT）作为高速器件引起了人们的广泛关注。在这项研究中，有人强烈建议，为进一步提高器件性能的HBT，降低基极电阻是非常重要的。从这一点出发，通过求解器件基本方程和混合π型等效电路模型，研究了降低基区电阻对超高基区掺杂InGaP/GaAs HBT静态和动态特性的影响。当基区空穴浓度增加到1.5 × 10 ~（-3）<21>cm ~ 3<-3>时，在少子寿命γ_n为10- 100 ps的条件下，电流增益可达10以上，电流增益截止频率f_T为110 GHz，最大振荡频率f_<max>T为160 GHz。利用SPICE模拟器和传播特性研究了开关特性。 ...更多信息基于<pd>这种考虑，采用新型的晶体生长技术：金属有机分子束外延（MOMBE），发展了重掺杂技术。碳（C）具有良好的稳定性和重掺杂能力，可以取代传统的铍（Be）和锌（Zn）等p型掺杂剂作为HBT基区掺杂剂。以三甲基镓（TMG）为原料，采用MOMBE技术制备了重掺碳的p型GaAs和InGaAs衬底材料，并对碳掺杂特性、电学、光学和结构特性进行了详细的研究。此外，磷化物材料，如InGaP和InP，由于其表面复合速度低的趋势，在本研究中也被提出作为HBT的新型发射极材料，并且研究了这些化合物的MOMBE生长与新的金属有机磷前体：叔丁基膦（TBP）。在高质量材料的生长中，与简单的热解相比，通过裂解池内加热的钽（Ta）进行的催化对于有效地分解TBP是重要的。用<0.5><0.5>裂解Si_2H_6研究了适用于HBT的In_ Ga_ P中Si掺杂的可控性。在MOMBE生长InP的过程中，TBP中的碳被掺入到InP中，并成为活性良好的施主，结合这些MOMBE生长技术，在国际上首次提出并制备了n型InP发射极和p型InGaAs基区掺碳的InP/InGaAs HBT。在共发射极静态特性方面，对于<CEO><fe><FE>发射极面积A_E为80 × 80 μ m^2的器件，在集电极电流密度J_C为0.15kA/cm ^2时，共发射极击穿电压BV_达到6V以上，小信号电流增益h_达到20，直流电流增益h_达到11<21><-3>。通过使用该器件结构，由于基极中的超高掺杂可以极大地降低基极电阻，因此强烈期望改善高频性能。事实上，对于基底厚度为15 nm的器件，h_<fe>为16，h_<FE>为12。在可靠性测量中，在所研究的范围内没有观察到电流增益的显著退化，表明碳作为p型掺杂剂的完美稳定性。总之，首次研究了具有独特原始结构的HBT的成功实现;具有碳掺杂InP发射极和碳掺杂InGaAs基极的InP/InGaAs HBT和具有超高碳掺杂基极（p=1.5*10^ cm^）的InGaP/GaAs HBT<21><-3>。少