GaAs Growth on Micro and Nano Patterned Ge/ Si1-XGeX and Si Surfaces
- PDF / 942,103 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 59 Downloads / 246 Views
A6.9.1
GaAs Growth on Micro and Nano Patterned Ge/ Si1-XGeX and Si Surfaces Ganesh Vanamu,1 Abhaya K. Datye,1 Ralph L. Dawson,2 and Saleem H. Zaidi3 Department of Chemical and Nuclear Engineering & Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, NM-87131 2 Center for High Technology Materials, 1313 Goddard SE, Albuquerque NM 87106 3 Gratings, Inc., 2700 B Broadbent Parkway, N.E, Albuquerque, NM 87107 1
ABSTRACT We show heteroepitaxial growth of GaAs on Ge/SiGe grown on nanometer-scale grating structures. Conventional lithography techniques were combined with reactive ion and wet-chemical etching to fabricate 1-D patterns of silicon posts. The quality of the GaAs layers was investigated using high-resolution x-ray diffraction (HRXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), photoluminescence (PL) and etch pit density (EPD) measurements. Our results show significant improvement in the quality of heteroepitaxial layers grown on nano patterned structures compared to those on the unpatterned silicon. The optical quality of the GaAs/Ge/SiGe on nano-scale patterned silicon was comparable to that of single crystal GaAs. INTRODUCTION There is a growing interest in integrating [1-6] optoelectronic GaAs with conventional Si integrated circuit technology. A lattice mismatch of 4.1% and a thermal mismatch of ~ 50% between them makes it difficult to grow high quality devices on the GaAs/Si7. So a buffer layer is necessary to integrate these two materials. Many different growth schemes [7-9] have been tried in order to achieve such an ideal buffer. The most promising scheme is the linearly graded buffer layer (Si1-xGex) [7, 10-11]. We have adopted the graded buffer approach to integrate GaAs on Si. The goal of this work is to grow high quality (defect free) heteroepitaxial GaAs Ge/SiGe/Si for electronic and optoelectronic devices. The quality of the GaAs is analyzed. The quality of the structures is analyzed for two samples of Ge/SiGe/Si namely; unpatterned silicon substrate and a nano-scale patterned silicon substrate (which has Ge with 4 × 106 cm-2 dislocation density). The photoluminescence (PL) of the GaAs epitaxial films was compared with that of single crystal GaAs used as a reference. EXPERIMENT The patterned substrates are fabricated on a 4”-diameter Si substrates off-cut 4~5 degrees in the direction, followed by growth of SixGe1-x, Ge and GaAs layers. Figure. 1(a) shows a SEM image of a patterned nano-scale grating on a silicon substrate. We used conventional and interferometric lithography techniques combined with reactive ion etching (RIE) and wet-chemical etching to fabricate Si structures. By subjecting this
A6.9.2
(a) (b) Figure. 1. SEM image of (a) Patterned nano-scale Si substrate (b) Cross-section of Ge/SixGe1-x on a nano-scale patterned Si. structure to 10% KOH etching (~70°C), sidewall surface roughness can be reduced by recovering planes. Heteroepitaxial growth of GaAs on Ge/SixGe1-x/Si layers as shown in Figure. 1(b) on the nanometer-scale
Data Loading...
