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

异质结双极晶体管（HBT）作为高速器件而备受关注，在这项研究中，强烈提出，为了进一步提高HBT的器件性能，降低基极电阻非常重要。良好约束的基极掺杂剂是实现高速HBT的关键结构参数之一。由此可见，降低基极电阻对超高高速InGaP/GaAs HBT静态和动态特性的影响通过求解基本器件方程和混合π型等效电路模型来研究掺杂基极。通过将基极空穴浓度增加到1.5x10^<21>cm^<-3>，假设电流增益估计超过10。预计少数载流子寿命gamma_n为10-100ps，电流增益截止频率f_T为110GHz，最大振荡频率f_<max>为160GHz。还使用SPICE模拟器研究了开关特性，并在该器件结构中实现了l ps/gate的传播延迟时间t_<pd>。基于此考虑，利用新型晶体开发了重杂质掺杂技术生长技术：金属有机分子束外延 (MOMBE) 代替传统的 p 型掺杂剂，例如 HBT 中的基底层铍 (Be) 和锌 (Zn)。 (C) 被提议作为一种新型基础掺杂剂，因为 MOMBE 采用三甲基镓 (TMG) 开发了重碳掺杂的 p 型 GaAs 和 InGaAs 作为基础材料，并且具有碳掺杂特性和电学特性。此外，由于具有低表面的趋势，本研究还提出了磷化物材料（例如InGaP和InP）作为HBT的新型发射极材料。使用新的金属有机磷前体：叔丁基膦 (TBP) 研究这些化合物的复合速度和 MOMBE 生长。在高质量材料的生长中，裂解池内加热钽 (Ta) 的催化对于有效分解还研究了适用于 HBT 应用的 In_<0.5>Ga_<0.5>P 中 Si 掺杂的可控性。通过使用裂解的Si_2H_6通过MOMBE与TBP生长InP，发现来自TBP的碳被结合并充当良好激活的供体。通过结合这些MOMBE生长技术，具有碳掺杂n-的InP/InGaAs HBT。世界上首次提出并制备了碳掺杂p型InP发射极和碳掺杂p型InGaAs基极。在共发射极静态特性方面，具有较大的共发射极击穿电压。对于具有发射极的器件，BV_<CEO>达到了 6 V 以上，并且在集电极电流密度 J_C 为 0.15kA/cm^2 时获得了 20 的小信号电流增益 h_<fe> 和 11 的直流电流增益 h_<FE>面积A_E为80*80mum^2。此外，具有超高碳掺杂基极的InGaP/GaAs HBT，其空穴浓度为首次实现了10^<21>cm^<-3>量级。通过使用该器件结构，由于超高掺杂，基极电阻可以大大降低，因此有望提高高频性能。事实上，对于基极厚度为 15 nm 的器件，h_<fe> 为 16，h_<FE> 为 12。在可靠性测量中，在研究的范围内没有观察到电流增益的显着下降。碳的完美稳定性结论是，成功实现了具有独特原始结构的具有碳掺杂InP发射极和碳掺杂InGaAs基极的Inp/InGaAs HBT以及具有超高碳掺杂基极的InGap/GaAs HBT（p=1.5）。 *10^<21>cm^<-3>) ，首次研究较少。