In the relentless pursuit of enhancing power electronics, researchers have long sought to optimize the performance of high electron mobility transistors (HEMTs). A recent study published in ‘Materials Research Express’, led by An-Chen Liu from the Department of Photonics and Institute of Electro-Optical Engineering at National Yang Ming Chiao Tung University, Hsinchu, Taiwan, has made significant strides in this area. The research focuses on the development of normally-off recessed gate AlGaN/GaN metal insulator semiconductor high electron mobility transistors (MISHEMTs), with a particular emphasis on the trade-off between threshold voltage (VTH) and maximum drain current (ID,max).
The study employed atomic layer etching (ALE) technology to fabricate recessed gate MISHEMTs with varying AlGaN remaining thicknesses of 2 nm, 3 nm, and 5 nm. The precision of the ALE process ensured minimal surface damage, a critical factor in maintaining device reliability. The results were striking: the device with a 5 nm AlGaN remaining thickness showcased an impressive ID,max of 347 mA mm−1, a VTH of +2.6 V, and a breakdown voltage (BV) of 830 V. In contrast, devices with thinner AlGaN layers (3 nm and 2 nm) exhibited significantly lower breakdown voltages of 120 V and 75 V, respectively.
According to Liu, “The key to achieving high performance and reliability in GaN-based power applications lies in understanding and optimizing the trade-off between threshold voltage and maximum drain current.” This optimization is crucial for the development of efficient and reliable power electronics, which are essential for the energy sector.
The study also utilized technical computer-aided design (TCAD) simulations to analyze the underlying mechanisms and electric field distributions within the devices. The simulations revealed that the hot electrons effect, under the influence of high electric fields, can promote electrons to overcome potential energy barriers, leading to trapping in the buffer, barrier, or insulating layers. This phenomenon degrades the off-state breakdown voltage capability, a critical factor in the performance of power devices.
The implications of this research are far-reaching. The optimization of recessed gate MISHEMTs could lead to more efficient and reliable power electronics, which are vital for the energy sector. As the demand for renewable energy sources continues to grow, the need for high-performance power electronics becomes increasingly important. This study provides a roadmap for future developments in the field, paving the way for more efficient and reliable power devices. The research, published in ‘Materials Research Express’, offers valuable insights into the optimization of GaN-based power devices, potentially revolutionizing the energy sector and beyond.