Improved trap-related characteristics on SiN<inf>x</inf>/AlGaN/GaN MISHEMTs with surface treatment

Abstract

In this paper, the reliable SiN x /AlGaN/GaN MISHEMTs on silicon substrate with improved trap-related characteristics have been well demonstrated. The devices with our proposed treatment method showed less deep-level traps and more Si surface donors at SiN x -AlGaN interface. The trap related device characteristics are also improved by using our optimized treatment method. The devices with proposed treatment method exhibit less current collapse and better positive bias temperature stability of threshold voltage. All the results suggest that the proposed treatment method is very effective to improve the slow-trap related device reliability.

Impact of gate insulator on the dc and dynamic performance of AlGaN/GaN MIS-HEMTs

“…V TH shift) are induced by positive gate voltage, suggesting the presence of traps between AlGaN barrier and dielectric under the gate [12][13][14][15]. This result is partially confirmed by Lin et al [16].…”

The role of SiN/GaN cap interface charge and GaN cap layer to achieve enhancement mode GaN MIS-HEMT operation

“…This positive interface charge between a dielectric layer (Al 2 O 3 , SiON, SiN x ) and an III-nitride material has been widely reported in the literature [29,30,31,32,33]. Different dielectric layer materials used as a passivation layer induce various positive interface charge densities [32,33].…”

“…These ionized donors incompletely neutralize the negative polarization charge at a barrier surface [27]. This positive interface charge between a passivation layer and III-nitride materials also helps to minimise the current collapse [30].…”

“…Therefore, in this work, we carried out a research on the effect of the positive interface charge between the SiN passivation layer and the GaN cap on the device performance to achieve an enhancement mode operation by increasing the thickness of the GaN cap layer up to 35 nm. The positive interface charge at the interface between dielectric (Al 2 O 3 , SiON, SiN x ) and III-nitride materials such as GaN, Al x Ga 1−x N, and AlInN [29,30,31,32,33] leads to the increase of a 2DEG density and improves the switching performance of GaN MIS-HEMTs. The relationship between V th and the positive interface charge is given by [31,33]: where Q f is the positive fixed charge at the interface between the passivation dielectric layer and the III-nitride layer, V th (MIS-HEMT) stands for the threshold voltage of a metal-insulator-semiconductor high-electron mobility transistor and C dielectric is the capacitance of a dielectric layer.…”