Correlation between the leakage current and the thickness of GaN‐layer of AlGaN/GaN‐HFET

Abstract

For further improvements in AlGaN/GaN heterojunction field-effect transistor performance, it is necessary to reduce the buffer leakage current of the GaN layer. We studied the correlation between the buffer leakage current and the thickness of GaN layers. Unintentionally doped GaN layers with different thicknesses from 0.2 µm to 2 µm were grown by metal organic chemical vapor deposition on SiC substrates. The buffer leakage current of the GaN layer was measured after deposition of ohmic metal contact and the dislocations were observed using a transmission electron microscopy. The thinner samples had a smaller buffer leakage current although a higher density of threading dislocations. We discussed the origin for the reduction in the buffer leakage current for the thinner GaN layers by assuming that the residual carrier in the GaN layer was compensated by dislocations.

The critical role of growth temperature on the structural and electrical properties of AlGaN/GaN high electron mobility transistor heterostructures grown on Si(111)

“…[30][31][32][33] To assess the insulating properties of the buffer layer at room temperature, we performed capacitance-voltage measurements using a mercury probe setup and current-voltage measurements between Ohmic contacts with a 100 m width and separated by a 110 m distance with a 150 nm deep mesa ͑results are reported in Fig. 8 and full symbols represent data observed for the same wafers͒.…”

Role of ZrO2 Passivation Layer Thickness in the Fabrication of High‐Responsivity GaN Ultraviolet Photodetectors

“…It indicates that the current transport in sample A cannot be explained by considering only the TE model. In case of III‐nitrides, threading dislocations are considered as an alternate conduction path, which often lead to high leakage current in Schottky diodes . The presence of a large density of dislocations ( N dis ) at the GaN/sapphire interface in similar HVPE grown 5 μm thick GaN samples including their adverse effect on the optoelectronic properties of devices made out of them is already reported by us .…”

“…Among them, MSM PDs are preferred due to their easy integration with field‐effect‐transistor (FET)‐based electronics and relatively fast response, which is a key figure of merit for PDs. However, GaN PDs often suffer from high leakage current, low photo‐to‐dark current ratio, and substantial persistent photoconductivity due to large density of threading dislocations and high background carrier concentration . A sluggish response of the device is often reported by researchers .…”

Study of the effects of GaN buffer layer quality on the dc characteristics of AlGaN/GaN high electron mobility transistors

“…[11][12][13] Also, the thinner GaN buffer layers on SiC have been reported to have higher threading dislocation density in the GaN, but lead to higher off-state breakdown voltages. 12,13 However, thick GaN buffer layers on sapphire and their impact on dc performance have not been widely studied.…”