High performance AlGaN/GaN HEMTs with AlN/SiN_xpassivation

Abstract

AlGaN/GaN high electron-mobility transistors (HEMTs) with 5 nm AlN passivation by plasma enhanced atomic layer deposition (PEALD) were fabricated, covered by 50 nm SiNx which was grown by plasma enhanced chemical vapor deposition (PECVD). With PEALD AlN passivation, current collapse was suppressed more effectively and the devices show better subthreshold characteristics. Moreover, the insertion of AlN increased the RF transconductance, which lead to a higher cut-off frequency. Temperature dependence of DC characteristics demonstrated that the degradations of drain current and maximum transconductance at elevated temperatures for the AlN/SiNx passivated devices were much smaller compared with the devices with SiNx passivation, indicating that PEALD AlN passivation can improve the high temperature operation of the AlGaN/GaN HEMTs.

Conduction Mechanisms at Interface of AlN/SiN Dielectric Stacks with AlGaN/GaN Heterostructures for Normally-off High Electron Mobility Transistors: Correlating Device Behavior with Nanoscale Interfaces Properties

“…On the other side, silicon nitride (SiN) has been used as a gate dielectric in MISHEMTs to reduce the leakage current. , Using SiN as a gate dielectric, Oka and Nozawa reached a V th > 4 V and a maximum field-effect mobility of 120 cm 2 V –1 s –1 . Moreover, both AlN and SiN showed interesting performances as a passivation layer on AlGaN/GaN heterostructures, reducing surface states density and limiting current collapse effects . Only recently, AlN/SiN bilayers were used in MISHEMTs both as a gate dielectric and passivation layer, exhibiting good properties in terms of current voltage ( I – V ) characteristics, current collapse, and dynamic R ON .…”

XPS study of impurities in Si‐doped AlN film

“…As a representative of III–V semiconductors, AlN is considered as one of the most important semiconductors because of its excellent optical and electrical properties, such as a large bandgap of 6.2 eV, high thermal and chemical stability, and low electron affinity. Especially, AlN integrated high‐Al‐content Al x Ga 1 − x N shows vast prospects in UV devices, such as light‐emitting diodes (LEDs), detectors, lasers and high electron‐mobility transistors (HEMTs) . In such devices, growing AlN film with high quality crystallinity and good surface morphology becomes a challenge, because of easy incorporation of residual impurities during material growth.…”

“…Especially, AlN integrated high-Al-content Al x Ga 1 À x N shows vast prospects in UV devices, such as light-emitting diodes (LEDs), [2,3] detectors, [4] lasers [5] and high electron-mobility transistors (HEMTs). [6,7] In such devices, growing AlN film with high quality crystallinity and good surface morphology becomes a challenge, because of easy incorporation of residual impurities during material growth. Oxygen, a most notably contamination, can increase the difficulty of doping remarkably and change the energy bandgap or Femi level, because oxygen contamination acts as a compensating defect and introduces deep localized acceptor states (DX centers), [8][9][10] which will bring huge barriers to improve performances of UV devices, such as quantum efficiency of LEDs, sensitivity of detectors and electron mobility of HEMT.…”

Comparative Study on Characteristics of AlGaN/GaN Metal–Insulator–Semiconductor High‐Electron‐Mobility Transistors

“…[13][14][15] This can bring in high densities of deep and slow interface states at Al 2 O 3 /(Al)GaN interface due to the formation of Ga-O bonds, which may degrade the device performance and reliability. [16] Depositing Al 2 O 3 in the upper layer, we hypothesize that metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT) with Al…”