Si基板上のエピタキシャルGaAs層の転位密度低減 : 熱サイクル成長法

抄録

Thermal cyclic growth (TCG) has been used to reduce the dislocation density of GaAs epitaxial layers grown on Si substrates by MOCVD. To evaluate the crystalline quality, we have used etch pit density (EPD) by molten KOH. To confirm the correspondence between the EPD and the dislocation density, we have also employed a transmission electron microscope (TEM) . The degree of the reduction depends on the cycle number N and the temperature difference between the growth temperature T_G and the lowest temperature T_L of the thermal cycles. EPD study reveals a maximum reduction of the dislocation density from 2×10^8 cm^-2 to 1×10^7 cm^-2 for N= 10 and TG = 700℃, T_L = 100℃. TEM study reveals that most threading dislocations in the GaAs grown by the TCG technique are confined on the (111) and (100) planes.