Uniform InGaAs micro-discs on Si by micro-channel selective-area MOVPE

We have improved in-plane uniformity of crystal shape for InGaAs micro-discs using a multi-step growth in micro-channel selective-area metal-organic vapor phase epitaxy on Si(111) substrates. The multi-step growth employs a gas flow sequence in which the partial pressure of a Ga source is modulated to control the initial nucleation and the growth mode. At the initial stage of growth, we grew InAs in order to obtain a single nucleus in each growth area. After the growth area was almost buried by InAs, Ga-rich InGaAs was grown to switch to a lateral growth mode. The Ga partial pressure was then reduced to continue lateral growth while avoiding 3-dimensional growth. This novel growth sequence suppressed unintended vertical growth of InGaAs islands and enhanced lateral growth; the averaged diameter was increased by 25%, the averaged height was reduced by 50% and the standard deviation of the height was reduced by 75%.