生长在尖晶石衬底上的GaN外延层的喇曼散射研究

在室温下测量了用MOVPE方法生长在尖晶石(MgAl_2O_4)衬底上的GaN外延层的一阶喇曼光谱。应用各种背散射和90°散射配置，测得了除低频E_2模外所有GaN的喇曼活性光学声子模。并且在X(Z,X)Z和X(Y,Y)Z配置下观测到了由A_1和E_2模混合形成的准TO和准LO模。所得结果与群论选择定则预计的一致。

GSMBE GaN 膜的电子输运性质研究

用NH_3作氮源的GSMBE方法在晶向为(0001)的α-Al_2O_3衬底上生长非有意掺杂的单晶GaN外延膜，GaN膜呈N型导电，室温时的最高迁移率约为120cm~2/(V·s),相应的非有意掺杂电子浓度为9.1×10~(17)cm~(-3)。对一些GaN膜进行了变温Hall测试，通过电阻率、背景电子浓度以及Hall迁移随温度的变化研究了GaN外延膜的导电机理。结果表明，当温度较低时，以电子在施主中心之间的输运导电为主；当温度较高时，以导带中的自由电子导电为主。

在GaSb衬底上生长c-GaN的初步研究

AES、XPS和XRD谱结果证明

GaN外延层的拉曼散射研究

测量了用MOCPE方法生长在尖晶石衬底上的GaN外延层和用MBE方法生长在蓝宝石衬底上的GaN外延层的喇曼散射,测量在室温下进行。

GaN材料的GSMBE生长

在国内首次用NH_3作氮源的GSMBE方法在α-Al_2O_3衬底上生长出了GaN单晶外延膜。GaN生长速率可达0.5μm/h。GaN外延膜的(0002)双晶X射线衍射峰回摆曲线的半高宽最窄为8arcmin，霍尔迁移率为50cm~2/V·s。对质量好的GaN膜，室温阴极发光谱上只有一个强而锐的近带边发光峰，谱峰位于372nm处，谱峰半高宽为14nm(125meV)。

MOVPE生长GaN的准热力学模型及其相图

基于准热力学平衡模型对以TMGa和NH_3为源的MOVPE生长GaN的过程进行了分析,并在此基础上计算了MOVPE生长GaN的相图。Gan的MOVPE相图由GaN(s)单凝聚相区、GaN(s)+Ga(1)双凝聚相区、表面会形成Ga滴和不会形成Ga滴的两个腐蚀区构成。着重讨论了生长温度、反应室压力、载气组分、NH_3分解率和V/III比对GaN单凝聚相区边界的影响。

Growth of GaN on magnesium aluminate substrate by LP-MOVPE

于2010-11-23批量导入

用于GaN生长的蓝宝石衬底化学抛光研究

于2010-11-23批量导入

高质量GaN材料的GSMBE生长

国家九五计划,中国博士后基金

GaN的MOVPE生长和m-i-n型蓝光LED的试制

国家863计划

GaN的MOCVD生长

GaN是重要的蓝光半导体材料。以TMGa和BH_3为源在(0112)α-Al_2O_3衬底上成功的用MOCVD方法生长了GaN外延层,研究了GaN的表面形貌与结晶学、电学和光学特性。GaN(2110)面的双晶回摆曲线衍射峰的最小半高宽已达16'。并观测到GaN所发出的紫外可见光波段的阴极荧光。

MOCVD growth of high quality crack-free GaN on Si(III) substrates

High quality crack free GaN epilayers were grown on Si(111) substrates. Low temperature AlN interlayer grown under low V/III ratio was used to effectively eliminate the formation of micro-cracks. It is found that tensile stress in the GaN epilayer decreases as the N/Al ratio decreases used for AlN interlayer growth. The high optical and structural qualities of the GaN/Si samples were characterized by RBS, PL and XRD measurements. The RT-PL FWHM of the band edge emission is only 39.5meV The XRD FWHM of the GaN/Si sample is 8.2arcmin, which is among the best values ever reported.

Effects of polarization field on formation of two-dimensional electron gas in (0001) and (11(2)over-bar0) plane AlGaN/GaN heterostructures

Photoluminescence (PL) and temperature-dependent Hall effect measurements were carried out in (0001) and (11 (2) over bar0) AlGaN/GaN heterostructures grown on sapphire substrates by metalorganic chemical vapor deposition. There are strong spontaneous and piezoelectric electric fields (SPF) along the growth orientation of the (0001) AlGaN/GaN heterostructures. At the same time there are no corresponding SPF along that of the (1120) AlGaN/GaN. A strong PL peak related to the recombination between two-dimensional electron gas (2DEG) and photoexcited holes was observed at 3.258 eV at room temperature in (0001) AlGaN/GaN heterointerfaces while no corresponding PL peak was observed in (11 (2) over bar0). The existence of a 2DEG was observed in (0001) AlGaN/GaN multi-layers with a mobility saturated at 6000 cm(2)/V s below 80 K, whereas a much lower mobility was measured in (11 (2) over bar0). These results indicated that the SPF was the main element to cause the high mobility and high sheet-electron-density 2DEG in AlGaN/GaN heterostructures. (C) 2004 Elsevier B.V. All rights reserved.

High-mobility Ga-polarity GaN achieved by NH3-MBE

GaN epilayers were grown on (0001) sapphire substrates by NH3-MBE and RF-MBE (radio frequency plasma). The polarities of the epilayers were investigated by in-situ RHEED, chemical solution etching and AFM surface examination. By using a RF-MBE grown GaN layer as template to deposit GaN epilayer by NH3-MBE method, we found that not only Ga-polarity GaN films were repeatedly obtained, but also the electron mobility of these Ga-polarity films was significantly improved with a best value of 290 cm(2)/V.s at room temperature. Experimental results show it is an easy and stable way for growth of high quality Ga-polarity GaN films.