藉由高介電質材料做表面鈍化及閘極絕緣層改善氮化鋁鎵/氮化鎵之高電子遷移率電晶體元件特性

Abstract

近幾年,氮化鋁鎵/氮化鎵高電子遷移率電晶體在高功率應用上廣受注目。然而在應用中，仍存在閘極漏電流以及電流崩潰這兩個現象影響著元件的表現及穩定度。多數的文獻已經證明使用金屬-絕緣體-半導體的閘極結構能夠有效地降低閘極漏電流以及電流崩潰。 因此，在本研究中，我們製作了二氧化鈰以及在不同電漿功率下成長的氮化鋁/氧化鋁雙層結構來製作金屬絕緣層氮化鎵高電子遷移率電晶體，並與傳統的氮化鎵高電子遷移率電晶體做比較。在閘極漏電流的表現上，使用二氧化鈰的金屬絕緣層結構能夠降低近4個數量級的漏電流，氮化鋁/氧化鋁的絕緣層結構，則可以降至近8個數量級的漏電流。其他的電性如最大汲極電流、臨限電壓、轉導亦有不錯的表現。除此之外，藉由電容的頻散現象以及遲滯效應的量測也得到不錯的絕緣層沉積品質。

In recent years, AlGaN/GaN high electron mobility transistors (HEMTs) have been widely studied for high power applications. However their performance and reliability are limited by the gate leakage current and drain current collapse. The utilization of insulator to form metal-insulator-semiconductor (M-I-S) gate structures has shown remarable improvements in reducing gate leakage current. In this study, we developed two kinds of MIS-HEMTs by using CeO2 and Al2O3/AlN dual layer with different plasma powers AlN deposition to compare the electric properties with conventional HEMT. The gate leakage current of CeO2 MOS-HEMTs is suppressed almost four orders of magnitude compared with conventional HEMTs in positive bias region. For Al2O3/AlN, both of MIS-HEMTs can mitigate almost eight orders of gate leakage current. Other DC characteristics such as maximum drain current, threshold voltage and tras-conductance also exhibited good performance in MIS-HEMT. Besides, we obtained good quality of insulator deposition as revealed by the frequency dispersion and hysteresis effect measurement in this study.