氮化鎵材料製程研究--p型氮化鎵歐姆接觸與准分子雷射蝕刻

Abstract

本論文主要探討氮化鎵材料製程研究，其中包括p型氮化鎵歐姆接觸與准分子雷射蝕刻。在歐姆接觸方面，利用p-GaN/Ni/Pd/Au結構，經由550℃，5分鐘氧氣環境熱退火處理後將，可得到良好歐姆接觸以及低特性電阻值為1.1×10-4Ω-cm2。Be離子高能量佈值之p型氮化鎵以相同合金結構作為歐姆接觸，未經退火處理可得到特性電阻為4.5×10-6Ω-cm2。 在准分子雷射的應用上，利用KrF准分子雷射蝕刻氮化鎵薄膜，可得到GaN分解所需臨界能量強度約為0.3 J/cm2，並且在3.75 J/cm2強度下有高蝕刻速率為82nm/sec。最後以能量強度1.0 J/cm2直接入射背面Sapphire基板，成功將基板從GaN薄膜剝離。

We study the process of GaN material including ohmic contact on p-GaN and Eximer laser etching of GaN. In ohmic contact, alloy consisted of Ni/Pd/Au film deposited on p-type GaN followed by heat treatment in oxygen condition. A good ohmic characteristic and specific contact resistance as low as 1.1 ×10-4Ω-cm2 was obtained at 550℃,5min. Another approach to achieving low-resistance ohmic contact is carrier concentration improvement of p-GaN by Be-implanted . A minimum ρc =4.5×10-4Ω-cm2 and perfect ohmic was obtained by Ni/Pd/Au contact without any heat treatment. In Eximer laser processing, both pulse energy and numbers of pulse of KrF laser were varied to etch the GaN film. By changing the pulsed energy at constant pulse energy, ablation of GaN surface was observed at threshold fluence of 0.3 J/cm2. A high etching rate of 82 nm/sec was obtained at fixed laser fluence of 0.3 J/cm2. Finally, we successfully separate GaN from GaN/sapphire structures using a KrF laser pulse of 1.0 J/cm2.