有機金屬氣相磊晶成長氮化鋁鎵之特性研究

Abstract

本論文是利用金屬氣相沈積磊晶方法，進行一系列之氮化鋁鎵薄膜，成長及電學特性研究。而在薄膜成長的過程中，我們固定III族（TMGa和TMAl），但改變V族（NH3）通入氣體的流率，發現在NH3流率為3000 sccm時，氮化鋁鎵薄膜成長具有最高的值；然而在流率2000 sccm所成長之樣品，其X-ray的半高寬值（270 arcsec）為最低，且其載子遷移率為最高（533 cm2/V-s）。利用2000 sccmNH3流率成長之AlGaN薄膜所製作成蕭基二極體後亦可以得到最佳之理想因子（1.10）以及最低的漏電流密度（2.0x10-8 A/cm2）。另外，我們並運用導納頻譜量測，我們觀察到此一樣品另一有新淺層缺陷，其能階位於導帶下方72 meV，成因可能是氮的空缺，亦有可能是氧、碳等其他雜質所造成，其原因仍須進一步之研究。

We have studied the electrical properties of a series of AlGaN films grown by metalorgainc chemical vapor deposition (MOCVD), of which the flow rate of TMGa and TMAl were maintained at constants while that of ammonia (NH3) were varied during the sample preparations AlGaN film exhibits good crystalline X-ray quality. FWHM as narrow as 270 arcsec and mobility as high as 533 cm2/V-s were obtained for the sample grown with NH3. The schottky diode made from the film shows excellent rectifying characteristics, the corresponding ideality factor and reverse leakage current are of 1.1and 2.0 X 10-8 A/cm2, respectively. Nevertheness, we do find a shallow defect, located at 72 meV below conduction band, This particular defect is believed to related closely to the presence of nitrogen, oxygen or carbon impurities in the AlGaN film.