Effects of a GaN cap layer on the reliability of AlGaN/GaN Schottky diodes

Abstract

In this paper, AlGaN/GaN‐ and GaN/AlGaN/GaN‐based Schottky barrier diodes (SBDs) were fabricated and studied for comparison. The recorded electrical characteristics of the devices show that the introduction of a GaN cap layer can evidently reduce the reverse leakage current and suppress the forward current decay of the devices. What is more important, the GaN/AlGaN/GaN‐based SBDs are capable of greatly alleviating the unrecoverable degradation of the reverse characteristics, which was observed in the device without a GaN cap layer when the device was under long time reverse dc stress. Detailed analyses were discussed.

a-Axis GaN/AlN/AlGaN Core–Shell Heterojunction Microwires as Normally Off High Electron Mobility Transistors

“…These improved properties are obviously attributed to the low leakage current by using the u-GaN cap. With the u-GaN, a lower ideality factor and a higher Schottky barrier height is enabled, as has been reported that by designing an InGaN, InGaAs, and GaN cap layers to enhance the Schottky barrier height in the literature. It was suggested that an electric field pointing from the surface of the GaN toward the AlGaN layer was formed by the negative polarization charge at the interface.…”

“…On the other hand, the decreased ideal factor due to the introduction of the GaN cap layer implies the suppression of the tunneling current. 51 These two effects lead to the decrease of the total leakage. Additionally, the extracted field-effect mobility is estimated to be 1153 and 1145 cm 2 /V/s at a V ds of 10 V for MOS-HEMT and MOS-HEMT with u-GaN cap structures, respectively (the Supporting Information).…”

“…As a result, the electric field bends the energy band of GaN cap upward, which reduces of the thermal emission leakage current. On the other hand, the decreased ideal factor due to the introduction of the GaN cap layer implies the suppression of the tunneling current . These two effects lead to the decrease of the total leakage.…”

Buckling on Fe‐Doped AlGaN/GaN High Electron Mobility Transistor Films after Laser Liftoff Process: Phenomena and Mechanism

“…Surface morphology of the GaN HEMT grown on a) an Fe‐doped buffer layer (50×) as reported in our previous work, [ 18 ] b) an Fe‐doped buffer layer (20×), and c) an unintentionally doped buffer layer after the LLO process.…”

“…[ 16 ] In the growth process of the Fe‐doped GaN buffer layer, the flow of the Fe source gas was 300 sccm; more details on the growth conditions can be found elsewhere. [ 17,18 ] The GaN HEMTs were debonded from the sapphire substrate using an LLO system comprising a set of optical lenses, working chamber, and KrF excimer laser that supplies UV light at a wavelength of 193 nm and a short pulse duration of 25 ns.…”