The charge trapping effects on AlGaN/GaN HEMTs under UV illumination are investigated using the pulsed current-voltage (I-V) measurement method. The test samples are unpassivated Schottky-gate HEMTs and metal-insulator-semiconductor HEMTs (MIS-HEMTs) with SiN gate dielectric. For HEMTs, the dominant charge trapping sources are the surface trap states, whereas, for MIS-HEMTs, they are trap states in the SiN gate dielectric and GaN buffer. When these devices are shined with the UV light, the drain current increases apparently in both samples owing to the generated photocurrent. By combining the UV illumination and pulsed I-V measurement, we find out the UV light has less effect on the surface charge trapping in the unpassivated HEMTs. Moreover, in MIS-HEMTs, we observe the charge trapping in the SiN gate dielectric becomes more serious under UV illumination, whereas the charge trapping in the GaN buffer is suppressed significantly. These findings are important for designing a GaN-based HEMT for photonic applications. In addition, the different responses of the surface-, buffer-, and gate-dielectric-related charge trapping to the UV light suggest that it would be easier to distinguish the trap types by introducing the UV illumination during the pulse measurement.

中文翻译：

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用脉冲 IV 测量研究在紫外光照射下对 AlGaN/GaN HEMT 的电荷俘获效应

使用脉冲电流-电压 (IV) 测量方法研究了在紫外线照射下对 AlGaN/GaN HEMT 的电荷俘获效应。测试样品是未钝化的肖特基栅极 HEMT 和具有 SiN 栅极电介质的金属绝缘体半导体 HEMT (MIS-HEMT)。对于 HEMT，主要的电荷俘获源是表面陷阱态，而对于 MIS-HEMT，它们是 SiN 栅极电介质和 GaN 缓冲层中的陷阱态。当这些器件用紫外光照射时，由于产生的光电流，两个样品的漏电流明显增加。通过结合紫外线照射和脉冲 IV 测量，我们发现紫外线对未钝化 HEMT 中的表面电荷俘获的影响较小。此外，在 MIS-HEMT 中，我们观察到在紫外线照射下，SiN 栅极电介质中的电荷俘获变得更加严重，而 GaN 缓冲器中的电荷俘获被显着抑制。这些发现对于设计用于光子应用的基于 GaN 的 HEMT 很重要。此外，表面、缓冲和栅极介电相关电荷俘获对紫外光的不同响应表明，通过在脉冲测量期间引入紫外照射，更容易区分陷阱类型。