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Growth of GaN Using Microwave-Excited N Plasma Method

采用微波激发 N 等离子体法生长 GaN

基本信息

批准号：
07805032
负责人：
KAI Ayako
金额：
$ 1.34万
依托单位：
Yamaguchi Unversity
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07805032/
关键词：
GaN Microwave-Excited Plasma Method Plasma Crystal Growth Photoluminescence Free exciton III-V族化合物半導体

项目摘要

Hexagonal GaN films were grown in gallium and nitrogen plasmas excited by microwaves. When the microwave power was lower than 500 W, the emission spectra from the plasma were composed of atomic N,neutral N_2 molecule (the first positive and second positive series transitions) and N_2^+ ion (the first negative series). The intensity of the atomic N peaks increased at the microwave power higher than 500 W and new strong peaks due to atomic Ga appeared. When the atomic Ga peaks arose, GaN was grown, whereas the surface of the Ga metal was nitrided when the peaks were absent.Although the resulting GaN films were composed of polycrystals, they showed strong peaks in the emission spectra near the band edge even at room temperature. The emission at 77 K and room temperature consisted of two components. One is attributable to the recombination of free excitons because the peak energy is almost equal to the free exciton energy. The other is ascribed to recombination related to localized states because the emission intensity saturates under high density excitation. The results of the time-resolved luminescence at 77 K and room temperature also revealed that the emission consists of two components, obeying a double-exponential decay. The first decay component is due to free exciton recombination and the slow one is ascribed to recombination of localized excitons. It is emphasized that the strong UV emission of free excitons is observable at room temperature.

在微波激发的镓氮等离子体中生长了异质结GaN薄膜。当微波功率低于500 W时，等离子体的发射光谱由N原子、中性N2分子（第一正、第二正系列跃迁）和N2 ^+离子（第一负系列跃迁）组成。当微波功率大于500 W时，N原子峰的强度增加，并出现Ga原子的强峰。当Ga原子峰出现时，GaN生长，而当Ga原子峰消失时，GaN表面被氮化。虽然所得GaN薄膜由多晶组成，但即使在室温下，它们在带边附近的发射光谱中也显示出强峰。在77 K和室温下的发射由两个分量组成。一种是由于自由激子的复合，因为峰值能量几乎等于自由激子能量。另一种归因于与局域态有关的复合，因为发射强度在高密度激发下饱和。在77 K和室温下的时间分辨发光的结果也表明，发射由两个分量，服从双指数衰减。第一个衰减分量是由于自由激子复合和缓慢的一个归因于局域激子的复合。强调了自由激子的强紫外辐射在室温下是可观察到的。