Growth of High Nitrogen Content GaAsN by Metalorganic Chemical Vapor Deposition
- PDF / 188,122 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 58 Downloads / 204 Views
Growth of High Nitrogen Content GaAsN by Metalorganic Chemical Vapor Deposition 1
J. C. Roberts, 2B. F. Moody, 2P. Barletta, 1M. E. Aumer, 1S. F. LeBoeuf, 1J. M. Luther and 1 S. M. Bedair 1 Dept. of Electrical & Computer Engineering, N. C. State University, Campus Box 7911, Raleigh, N. C. 27695-7911. 2 Dept. of Materials Science and Engineering, N. C. State University, Campus Box 7907, Raleigh, N. C. 27695-7907
ABSTRACT
The incorporation of a high percentage of nitrogen in the GaAs lattice has been the subject of recent interest to reduce the bandgap while maintaining the nearly lattice matched condition to GaAs. We will report on the metalorganic chemical vapor deposition (MOCVD) of GaAsN using trimethylgallium (TMG), tertiarybutylarsine (TBA) and dimethylhydrazine (DMHy) organometallic sources in a hydrogen-free carrier gas. A nitrogen concentration as high as ~8% in GaAsN was achieved. The effect of nitrogen concentration on the structural, optical and surface properties of GaAsN films will be discussed.
INTRODUCTION
Recently, the InxGa1-xAs1-yNy material system has gained attention for use in optoelectronic devices [1,2,3]. The In and N mole fractions in this quaternary system can be chosen to maintain a lattice matching condition to GaAs while achieving a ~1eV bandgap, which is of interest for increasing the efficiency of tandem solar cells by using InxGa1-xAs1-yNy as the third layer in a standard GaAs/Ga0.5In0.5P tandem solar cell [4]. The InxGa1-xAs1-yNy system is also becoming a primary material system for long wavelength laser diodes with excellent high temperature performance. However, only small nitrogen concentrations have been achieved by metalorganic chemical vapor deposition (MOCVD) of these materials due to the large miscibility gap. Several growth approaches have been applied to improve the nitrogen incorporation in this material system. High nitrogen content has been reported by using gas-source molecular beam epitaxy (GSMBE) in which radio frequency energy is used to generate active N species from an N2 source [5]. Increases in N incorporation were achieved using dimethylhydrazine (DMHy) and replacing AsH3 with tertiarybutylarsine (TBA). The lower cracking temperature of the column V organometallic sources DMHy and TBA allows lower temperature growth of GaAsN that can lead to higher nitrogen content [6]. The majority of research detailing the MOCVD growth of GaAs1-yNy indicates the use of H2 as the carrier gas, with nitrogen content as high as 5.6% reported [7]. In this work we will report that by substituting N2 for H2 as the carrier gas, nitrogen content in GaAsN as high as 8% can be achieved.
H1.9.1
EXPERIMENTAL DETAILS
All materials were grown by MOCVD in a commercial Thomas Swan system equipped with a horizontal fused silica research reactor at pressures ranging from 700 torr to 1 atmosphere. Trimethylgallium (TMG) was used as the column III precursor, while TBA and DMHy were used as column V precursors. Column V organometallic sources were chosen not only for safety concerns, but al
Data Loading...
