Design of Normally OFF AlGaN/GaN HEMT using Double Quantum Well Structure with Improved Breakdown Characteristics

An AlGaN/GaN based high electron mobility transistor (HEMT) is considered as an excellent candidate for future power devices due to its high breakdown voltage, high saturation drain current and low on resistance (Ron). The conventional AlGaN/GaN heterostructures are inherently normally ON devices but normally off operation (enhancement mode) is often desired for fail safe operation and ease of design. For safety and OFF mode power saving concerns, it is ideal for a HEMT to be normally OFF device where the channel will not conduct without any gate bias.However, current collapse, i.e., dispersion of drain current or increased dynamic Ron is regarded as one of the most critical issue to be solved in normally-off devices. Even though there have been remarkable improvements in growth and device technologies it is still essential to find out the reason behind current collapse and ways to get rid of it. In this work a normally off HEMT using double quantum well has been investigated. In order to suppress current collapse and enhance the breakdown voltage, a field plate structured device along with a SiN passivation layer has been studied.