An AlGaN/GaN HEMT by a reversed pyramidal channel layer: Investigation and fundamental physics

Abstract

AbstractIn this paper, an AlGaN/GaN HEMT with a reversed pyramidal channel layer (RPC‐HEMT) is proposed. The main purpose of the paper is an increase in the breakdown voltage of a conventional HEMT (C‐HEMT) to be suitable in high‐power applications. In the RPC‐HEMT, a reverse pyramidal channel layer in the high electric field traps the energetic carriers that cause the transistors to break. The steps decrease the carrier concentration across the two‐dimensional electron gas (2DEG) channel layer, especially under the gate contact. Therefore, the critical electrical field reduces by the uniform division of carrier mass and improves the breakdown voltage of the RPC‐HEMT by 32%. Besides, the maximum output power density of the new transistor improves compared with the conventional one. In addition, the radio frequency (RF) characteristics such as the cutoff frequency and maximum oscillation frequency of the RPC‐HEMT improve by the decline in the gate‐source capacitance. This article provides kink effects with the output reflection coefficient (S22) and the short‐circuit current gain (h21) to show how this anomalous phenomenon affects high‐frequency performance of devices. Finally, the proposed method makes the RPC‐HEMT appropriate for high‐power and high‐frequency applications.