A n-ZnO/p-Diamond Heterojunction Field Effect Transistor with a p-Type Buried Layer

In this paper, we propose and optimize a n-ZnO/p-diamond heterojunction field-effect transistors with a p-type buried layer in the gate-drain region (PBL-FET). Compared with the drift layer, the buried layer of the device is a highly doped p-type diamond region with a distance (d) away from the gate metal. We focus on the evaluation of the doping concentration, thickness of the buried layer and the d value to obtain the optimal device performances. Our simulation results show that with a doping concentration of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1\times 10^{17}\text{cm}^{3}$</tex> and a d value of 7 µm, the device achieved the excellent Baliga's figure of merit of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$8.26\text{MW}/\text{cm}^{2}$</tex>. Compared with the recessed gate n-ZnO/p-diamond heterojunction FET without PBL layer, the new structure proposed in this paper can well reduce the on-resistance, increase the breakdown voltage and provide more possibilities for high performance diamond-based devices.