鈦鎢氮化物和鎢氮化物在n-型氮化鎵半導體上蕭特基接觸之研究

Abstract

本論文係首次以反應式直流濺鍍法將鈦鎢氮化物和鎢氮化物濺鍍到n型氮化鎵半導體上，探討在不同退火溫度下，其蕭特基接觸的特性。 鈦鎢氮化物蕭特基接觸，經攝氏650度，10秒的快速退火後，其理想係數和能障高度分別為1.14及0.76電子伏特，但經攝氏750度和850度的快速退火後，其蕭特基特性即變差。由二次離子質量能譜儀分析顯示，在攝氏750度以上退火，鈦鎢氮化物與氮化鎵半導體之間有相互擴散的現象。 鎢氮化物在氮化鎵半導體上可形成熱穩定性極佳的蕭特基接觸。由二次離子質量能譜儀分析顯示經由攝氏850度，10秒的快速退火，鎢氮化物與氮化鎵之界面仍很穩定，能障高度維持在0.80電子伏特，而其蕭特基二極體之理想係數則維持在1.09。 比較鈦鎢氮化物和鎢氮化物的特性，可知鎢氮化物是較適合作為n型氮化鎵半導體的蕭特基接觸材料。

A comprehensive study of titanium tungsten nitride and tungsten nitride Schottky contacts on n-type GaN has been made. Both TiWNx and WNx film were deposited by reactive dc sputtering method, the electrical and physical characteristics of the Schottky contact were investigated as a function of annealing temperature. The TiWNx Schottky contact was only thermally stable up to 650℃, the values of ideality factor and barrier height after 650℃ annealing were about 1.14 and 0.76 eV respectively. The Schottky diode characteristics degraded after 750℃ and 850℃ annealing due to interdiffusion between TiWNx and GaN, as indicated by SIMS analysis. The WNx Schottky contact exhibited excellent electrical characteristic even after 850℃ annealing. The ideality factor and the barrier height remained 1.09 and 0.80 eV respectively after 850℃ annealing. Experimental results of this work indicated that WNx is a better Schottky contact material for n-type GaN.