The growth of GaAs, AlGaAs, and selectively doped AlGaAs/GaAs heterostructures by metalorganic vapor phase epitaxy using tertiarybutylarsine

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Abstract
The prevention of disastrous leakage of AsH3 is a requirement for metalorganic vapor phase epitaxy systems. Less hazardous organoarsine has been investigated as an alternative to AsH3 , and recently, tertiarybutylarsine (tBAs) has been used as an arsenic source. So far the use of tBAs has been restricted to fundamental experiments. The growth of GaAs, AlGaAs, and selectively doped AlGaAs/GaAs heterostructures has been studied using tBAs and AsH3, and the properties of the epilayers grown using both sources have been compared. From the PL spectra at 4.2 K, it was determined that GaAs films using tBAs were of high purity and equivalent to those using AsH3. The properties of AlGaAs grown using tBAs are as good as those using AsH3. A higher V/III ratio results in high-quality AlGaAs layers. The epitaxial uniformity of growth rate and AlAs mole fraction along a wafer using tBAs was poorer than those using AsH3 due to vapor phase reactions in the trimethylgallium-tBAs mixture. However, the increase of total gas flow rate in the reactor has the effect of improving uniformity. The activation efficiency of Si in AlGaAs is the same for both sources. The properties of heterostructures grown using tBAs are similar to those using AsH3. The sheet carrier concentration and electron mobility at 77 K with a spacer layer thickness of 35 Å were 9.5×1011 cm−2 and 48 000 cm2 V−1 s−1, respectively. This suggests that tBAs can be used as an alternative to AsH3, for growing device-quality GaAs and AlGaAs.