Charge balancing in GaN-based 2-D electron gas devices employing an additional 2-D hole gas and its influence on dynamic behaviour of GaN-based heterostructure field effect transistors

Abstract

GaN-based heterostructure FETs (HFETs) featuring a 2-D electron gas (2DEG) can offer very attractive device performance for power-switching applications. This performance can be assessed by evaluation of the dynamic on-resistance Ron,dyn vs. the breakdown voltage Vbd. In literature, it has been shown that with a high Vbd, Ron,dyn is deteriorated. The impairment of Ron,dyn is mainly driven by electron injection into surface, barrier, and buffer traps. Electron injection itself depends on the electric field which typically peaks at the gate edge towards the drain. A concept suitable to circumvent this issue is the charge-balancing concept which employs a 2-D hole gas (2DHG) on top of the 2DEG allowing for the electric field peak to be suppressed. Furthermore, the 2DEG concentration in the active channel cannot decrease by a change of the surface potential. Hence, beside an improvement in breakdown voltage, also an improvement in dynamic behaviour can be expected. Whereas the first aspect has already been demonstrated, the second one has not been under investigation so far. Hence, in this report, the effect of charge-balancing is iscussed and its impact on the dynamic characteristics of HFETs is evaluated. It will be shown that with appropriate device design, the dynamic behaviour of HFETs can be improved by inserting an additional 2DHG

Lateral Charge Transport in the Carbon-Doped Buffer in AlGaN/GaN-on-Si HEMTs

“…The proposed model to explain this behavior is that the vertical field results in the formation of a 2-D hole gas (2DHG) layer at the heterojunction between the bottom of the GaN:C layer and the AlGaN based strain relief layer (SRL). 2DHGs have been widely discussed as occurring at GaN based heterojunctions and have been exploited in active devices [22]- [26]. Here we show for the first time that a parasitic 2DHG within the buffer can also have a strong impact on the substrate bias dependence.…”

Possibility of Reducing The On-resistance in 1 kV-class Lateral Superjunction Power Devices based on III-V Semiconductors

“…devices), (2) devices with superjunctions (SJ), 2,3 and (3) devices with hetero superjunctions (HSJ). [4][5][6][7][8][9] Particularly, GaAs lateral HSJ devices that were considered unsuitable for high voltage applications are shown to promise excellent characteristics.…”

Possibility of reducing the on‐resistance in 1 kV‐class lateral superjunction power devices based on III‐V semiconductors

“…In so doing, focus is placed on electron drift region; specifically, the paper examines and evaluates (1) devices with uniform drift region (Uni. devices), (2) devices with superjunctions (SJ), and (3) devices with hetero superjunctions (HSJ) . Particularly, GaAs lateral HSJ devices that were considered unsuitable for high voltage applications are shown to promise excellent characteristics.…”