Investigation of inhomogeneities in (Al, Ga, In)N heterostructures by STEM and cathodoluminescence

被引:13
作者
Lakner, H [1 ]
Liu, Q
Brockt, G
Radefeld, A
Meinert, A
Scholz, F
机构
[1] Gerhard Mercator Univ Duisburg, Werkstoffe Elektrotech, D-47048 Duisburg, Germany
[2] Univ Stuttgart, Inst Phys, D-70550 Stuttgart, Germany
来源
MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY | 1998年 / 51卷 / 1-3期
关键词
STEM; cathodoluminescence; inhomogeneities;
D O I
10.1016/S0921-5107(97)00227-4
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Wurtzite (Al, Ga, In)N heterostructures grown by metal organic vaper phase epitaxy (MOVPE) were studied using quantitative analytical scanning transmission electron microscopy (STEM) and cathodoluminescence (CL). The STEM results can be summarized as follows. The interfaces in e.g. In0.12Ga0.88N/GaN single quantum wells (SQWs) appear to be asymmetric. The lower interface in the growth direction is more abrupt than the upper one, where a grading in the In concentration is significant. We found composition fluctuations in the nanometer range within the InGaN QWs, which are supposed to cause the localized exitonic behavior of the observed photoluminescence (PL) emission. In the sample with 17 nm thick InGaN QWs we observed relaxation effects, which are not present in the thin QWs of 2 nm thickness. CL results on both InGaN/GaN and AlGaN/GaN SQW structures show generally inhomogeneous emission intensity in panchromatic CL micrographs on a 1 mu m scale, which is related to local variations of the interface quality. CL spectra recorded from defect sites in AlGaN/GaN SQWs are dominated by the so-called 'yellow-emission'. In the samples containing InGaN layers, the grown-in hexagonal pyramids and mesa-like structures as well as micropipes were commonly observed. (C) 1998 Elsevier Science S.A. All rights reserved.
引用
收藏
页码:44 / 52
页数:9
相关论文
共 11 条
[1]  
BROCKT G, 1997, IN PRESS P 10 C MICR
[2]   Solid phase immiscibility in GaInN [J].
Ho, IH ;
Stringfellow, GB .
APPLIED PHYSICS LETTERS, 1996, 69 (18) :2701-2703
[3]   Characterization of MOVPE-grown (Al,In,Ga)N heterostructures by quantitative analytical electron microscopy [J].
Lakner, H ;
Brockt, G ;
Mendorf, C ;
Radefeld, A ;
Scholz, F ;
Harle, V ;
Off, J ;
Sohmer, A .
JOURNAL OF ELECTRONIC MATERIALS, 1997, 26 (10) :1103-1108
[4]   Characterization of III-V semiconductor interfaces by Z-contrast imaging, EELS and CBED [J].
Lakner, H ;
Bollig, B ;
Ungerechts, S ;
Kubalek, E .
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 1996, 29 (07) :1767-1778
[5]  
MIDDELTON PG, 1997, MATER RES SOC S P, P449
[6]  
MOHAMMED A, 1997, IN PRESS P 10 OXF C
[7]  
NAKAMURA S, 1996, JPN J APPL PHYS, V35, P217
[8]  
NARUKAWA Y, 1996, P MRS FALL M BOST MA
[9]  
SCHOLZ F, P MRS FALL M 1996 S
[10]  
Spence J.C.H., 1992, Electron Microdiffraction, DOI [10.1007/978-1-4899-2353-0, DOI 10.1007/978-1-4899-2353-0]