OPTICAL-PROPERTIES OF QUANTUM-WELLS GROWN UPON GAS SOURCE MOLECULAR-BEAM EPITAXY LOW-TEMPERATURE BUFFERS

GaAs/AlGaAs quantum wells are grown on gas source molecular-beam epitaxy (GSMBE) grown low-temperature buffers (LTB). Changes in LTB growth conditions produce noticeable changes in photoluminescence (PL) intensity and linewidths of the quantum wells. Layers grown at low temperatures (200-300-degrees-C) incorporate excess arsenic which outdiffuses during subsequent quantum well growth. Reflection high energy electron diffraction and PL results are utilized to show strain and arsenic outdiffusion from the LTBs. Excess arsenic incorporation during the growth of GaAs at low temperatures is explained in terms of the association reaction of As2 to form As4 at the surface. The optimum V/III ratio for growth of LTB by GSMBE is discussed.