基区设计对InGaP/GaAs HBT热稳定性的影响

研究了不同基区设计对多发射极指结构功率InGaP/GaAs异质结双极型晶体管热稳定性的影响。以发生电流增益崩塌的临界功率密度为热稳定性判定标准,推导了热电反馈系数Φ、集电极电流理想因子η和热阻Rth与基区掺杂浓度NB、基区厚度dB的理论公式。基于TCAD虚拟实验,观测了不同基区掺杂浓度和不同基区厚度分别对InGaP/GaAs HBT热稳定性的影响。结合理论公式,对仿真实验曲线进行了分析。结果表明,基区设计参数对热稳定性有明显的影响,其影响规律不是单调变化的。通过基区外延层参数的优化设计,可以改进多指HBT器件的热稳定性,从而为多指InGaP/GaAs HBT热稳定性设计提供了一个新的途径。

Effect of the Base Design on the Thermal Stability of InGaP/GaAs HBTs

The effect of different base designs on the thermal stability of multi-emitter-finger structure power InGaP/GaAs heterojunction bipolar transistor(HBT) was researched.Taking the critical power density at the collapse of the current gain as the criteria of the thermal instability,the theoretical formulas of the thermal-electrical feedback coefficient Φ,collector current ideality factor η and thermal resistance Rth were derived with the base doping concentration NB and base thickness dB.Based on the TCAD virtual experiment,the effect of different base doping concentrations and different base thinknesses on the thermal stability of InGaP/GaAs HBTs were observed.And then,the simulation curves were analyzed combined with the theoretical formulas.The results show that the thermal stability of the multi-finger InGaP/GaAs HBT is obviously effected by the base design parameters,and the influence rule is not monotonic.Thus,the thermal stability of the HBT device can be improved by the optimization design of the base epitaxial layer,providing a new method for the thermal stability design of the multi-finger InGaP/GaAs HBT.