Arsenic Incorporation in Gallium Nitride grown by Metalorganic Chemical Vapor Deposition using Dimethylhydrazine and Ter
- PDF / 113,503 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 5 Downloads / 262 Views
Arsenic Incorporation in Gallium Nitride grown by Metalorganic Chemical Vapor Deposition using Dimethylhydrazine and Tertiarybutylarsenic S. Kellermann,1,2 K. M. Yu,1 E. E. Haller1,2 and E. D. Bourret-Courchesne1 1
Center of Advanced Materials, Materials Science Division, Lawrence Berkeley National Laboratory, MS 2-200, 1 Cyclotron Rd., Berkeley, CA 94720.
2
Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720.
ABSTRACT MOCVD growth of As-doped GaN using dimethylhydrazine, triethylgallium and tertiarybutylarsenic has been investigated. A maximum doping concentration of 4.0 × 1019cm-3 at growth temperatures between 600ºC and 800ºC was obtained. At 1000ºC the As doping level dropped below the SIMS detection limit of ~1.0 × 1017cm-3. The As incorporation depended only weakly on variations of the V/III molar flow ratio between 11 and 61. Raising the As/V molar flow ratio from 0.01 to 0.06 increased the As concentration which then decreased by further increase to 0.11. Different morphologies of the layers were found depending on the growth conditions. A surfactant-like behavior of As was observed leading to smooth GaN films grown on top of the As-doped GaN layer. Two characteristic luminescence peaks at 3.31 eV and 3.425 eV were found for samples doped with As below 900ºC. These spectral features are believed to originate at extended lateral defects - presumably stacking faults. INTRODUCTION In recent years semiconductors containing both arsenic and nitrogen on the anion sublattice, namely GaAsN and InGaAsN, have attracted much scientific and technical interest.1,2 They exhibit an unusually large band gap bowing and are attractive candidates for a variety of optoelectronic applications.3,4 The growth of these materials is, however, challenging due to the large miscibility gap found in group-III As-N-compounds.5,6 Only a small number of studies of the synthesis of N-rich GaAsN alloys have been conducted.7,8,9 Some of these deal with attempts of metalorganic chemical vapor deposition (MOCVD).10,11 Ammonia, the N-source of choice for MOCVD growth of group-III nitrides, is not fully decomposed at the commonly used reaction temperatures of 1000ºC to 1100ºC and stoichiometric growth requires V/III molar flow ratios of around 5000. Dimethylhydrazine (DMHy), which is completely decomposed at 800ºC, is therefore an interesting alternative for growth of ternaries at lower temperature. In fact, (In)GaAs compounds, grown by MOCVD that are either doped or alloyed with N use primarily DMHy as N-source.2,4,12 In this paper we report on the MOCVD growth of As-doped GaN using DMHy and tertiarybutylarsenic (TBAs) as precursors to nitrogen and arsenic. The As incorporation as functions of various growth conditions (As/V molar flow ratio, growth temperature, and V/III molar flow ratio) was investigated. EXPERIMENT GaN was deposited on sapphire (c-plane) substrates using a low-pressure chemical vapor deposition reactor. Triethylgallium (TEGa) and high purity water-free DMHy, were used as g
Data Loading...
