Correlation of AlGaN/GaN high-electron-mobility transistors electroluminescence characteristics with current collapse

Abstract

We report on the correlation between the electroluminescence and current collapse of AlGaN/GaN high-electron-mobility transistors (HEMTs). Standard passivated devices suffering from severe current collapse exhibited high-intensity whitish electroluminescence confined near the drain contact. In contrast, devices with reduced current collapse resulting from oxygen plasma treatment or GaN capping showed low-intensity reddish emission across the entire gate–drain access region. A qualitative explanation of this observed correlation between the current collapse and electroluminescence is presented. Our results demonstrate that electroluminescence analysis is a powerful tool not only for identifying high-field regions but also for assessing the degree of current collapse in AlGaN/GaN HEMTs.

Bias-Dependence of Electroluminescence in AlGaN/GaN High-Electron-Mobility Transistors on SiC Substrate

“…HEMTs with high energy hot electrons exhibited a high-intensity whitish EL, whereas HEMTs with relatively low energy hot electrons exhibited a weak reddish EL. [19] On the other hand, in our study, we successfully observed EL color changed from a low-intensity reddish to a high-intensity whitish in one HEMT with increased Vds. [21] These changes in EL color are attributed to a shift of high electric field from the gate to the drain edge.…”

“…[28] The detectable wavelength range of the SI-CCD camera is 300-1100 nm, so the EL related with the hot electrons in HEMTs can be observed with the PHEMOS ○ R -1000. [19][20] Figures 4 (a emission peak is at the gate. When the Vds increases from 30 to 40 V, the EL of the HEMT shifts 0.5 µm from the gate center toward the drain edge, shown in Fig.…”

“…[18] The change in EL color is related with the density of trapped electrons, which affects the potential profile in the gate-drain access region. [19,21] As shown in Fig. 6 (a), under a Vds of 30 V, small amount of electrons is trapped near the gate, which results in a low current collapse in the HEMT, depicted in Fig.…”

“…Electroluminescence (EL) measurement is a powerful method for analysis of electric field distribution in AlGaN/GaN HEMTs. [15][16][17][18][19][20][21][22][23][24][25] The high electric field region in HEMTs can be identified by EL location. In the case of HEMTs with severe current collapse, EL was observed at the drain edge.…”

“…Furthermore, some literatures mentioned when HEMTs was under continuous biasing, EL shifted from the gate edge toward the drain electrode, indicating a transition of the high electric field region. [17][18][19] In addition, EL color was used to explore a distribution of an electron energy. HEMTs with high energy hot electrons exhibited a high-intensity whitish EL, whereas HEMTs with relatively low energy hot electrons exhibited a weak reddish EL.…”