Feasibility of the LPE Growth of AlxGayIn1-x-yP on GaAs Substrates

The maximum direct bandgap energy of Al x Ga y In 1- x - y P lattice-matched to GaAs is found to be 2.17 eV at x =0.21 and y =0.34. This is the largest value among the III-V compounds with the zinc-blende structure. The phase diagram is calculated of the quaternary system Al–Ga–In–P. It is predicted that the LPE growth of Al x Ga y In 1- x - y P will encounter serious difficulties resulting from the extremely large segregation coefficient of aluminum. In fact, experiments have shown that aluminum is not incorporated into the crystals grown from the quaternary solutions because of the instant depletion of aluminum at the very early stage of the cooling process.