Effects of growth conditions on InAs quantum dot formation by metal-organic chemical vapor deposition using tertiarybutylarsine in pure N₂ ambient

Self-assembled InAs quantum dots (QDs) on GaAs grown by metal-organic chemical vapor deposition using tertiarybutylarsine as arsenic source in pure nitrogen ambient have been investigated in detail. Effects of the growth conditions, e.g., substrate temperature and inlet precursor flux, on the QD formations have been studied. A temperature window for growing high density (1.3 × 10¹⁰ cm^-2) of QDs with the trimethylindium (TMIn) flow flux of 30 SCCM (SCCM denotes cubic centimeter per minute at STP) is observed from 440 to 460 °C. High density, ≥1.3×10¹⁰ cm^-2, of the QDs have been grown at higher temperature, 500°C, with the higher TMIn flux of 75 SCCM, but the formed QDs are not very uniform. To improve the QD uniformity and density further, a two-step growth method has been proposed and investigated. Using the two-step growth method, the dot density achieves 30% higher than that of the QDs grown by using the normal Stranski-Krastanow growth method. The size of the QDs formed by the two-step growth is larger and more uniform.