同電子性銦摻雜對P型氮化鎵薄膜之影響

Abstract

本論文主要探討銦摻雜對p型氮化鎵薄膜的影響，針對含銦p型氮化鎵薄膜以及純鎂p型氮化鎵薄膜作一系列的研究。不論是純鎂p型氮化鎵薄膜或是含銦p型氮化鎵薄膜，其冷激光光譜均由一較寬2.78eV頻譜主導。從光學顯微鏡及電流電壓特性曲線來看，銦摻雜後的p型氮化鎵薄膜不但表面變得比較平坦，而且具有比較良好的歐姆特性。除此之外，由室溫霍爾電性量測結果，發現含銦p型氮化鎵薄膜的電洞濃度均比純鎂p型氮化鎵薄膜的電洞濃度高，尤其當鎂流率在250scccm時，含銦p型氮化鎵薄膜的電洞濃度可達7.32´1017cm-3。由變溫霍爾實驗數據顯示，含銦p型氮化鎵薄膜電洞濃度的提昇主要與受子活化能降低、補償率下降以及有效淺階受子濃度增加有關，與固態鎂原子的融入率無直接相關。

We have investigated the isoelecetronic indium doping effects of Indium on p-type GaN films. Two sets of samples were prepared：one is pure Mg-doped GaN film, the other is Mg-In codoped GaN film. Whether Indium is doped or not, the photoluminescence spectra of as-grown p-type GaN films all show one broad emission peak around 2.78eV, which indicating Mg-rich in all of our p-type GaN samples. Besides, it is interesting to note that the hole concentration of Mg-In codoped GaN is higher than that of Mg-doped one based on room-temperature Hall measurement data. The optimum hole concentration is 7.32´1017cm-3. We believe the increase of the hole concentration in these indium doped p-GaN films can be attributed primarily to the reduction of the acceptor activation energy, the decrease of compensation effects as well as effective incorporation of Mg atom as shallow acceptor, rather than deep impurity, not directly related to the Mg solid concentration in the film.