Si衬底上MBE长成的GaAs中剩余应力起源的研究(英文)

<正> High qualities of GaAs layers directly grown on Si substrates have been obtained by MBE. The residual stress in those MBE grown GaAs layers on

A Study on the Origin of Residual Stress in MBE Grown GaAs Layers on Si Substrates

High qualities of GaAs layers directly grown on Si substrates have been obtained by MBE. The residual stress in those MBE grown GaAs layers on 4° off (100) toward <110> Si substrates has been studied by using a double crystal X-ray rocking curve (DCRC) and photoluminescence (PL) techniques. DCRC results show that the residual stress in GaAs layers of 1 to 4μm in thickness appears a biaxial tensile stress in a range of 0.2 to 4kbar, which is attributed to the interaction of mismatch in lattice constant and thermal expansion coefficient. According to the stresses in GaAs/Si system contributed by the biaxial compression stress caused by lattice mismatch and the biaxial tensile stress caused by the mismatch of thermal expansion, a qualitative equation is proposed to interpret the results. A misorientation in a range of 0.1'-59' between (100) GaAs layer and (100) Si substrate has also been found from DCRC measurements.PL characteristics of GaAs layers on Si were carried out at the constant or variation temperature from 25K to 260K. For comprison, MBE grown GaAs on GaAs with similar thickness and a free carrier concentration of 3×1017cm-8 was also mounted on the sample holder with GaAs on Si samples side by side while PL in measuring. 90meV shift toward lower energy direction of GaAs band energy has been observed at 77K. It may be due to the split of light-hole valence and heavy-hole valence of GaAs by the biaxial stresses. PL results slso show that the residual stress in GaAs layers on Si decreases with temperature increasing. This is in good agreement with that of the equalitative equation we proposed