Reduction of Thermal Stress in Mbe Grown GaAs/Si by Patterning

Abstract

AbstractThe biaxial tensile stress of 2.65 kbar in as-grown GaAs/Si for T < 100K is reduced by post-growth patterning of the GaAs and the reduction in stress, as determined by photoluminescence and cathodoluminescence, is dependent on the pattern size and shape. For stripe patterns less than 15 gm wide the stress is largely uniaxial with stress relief normal to the stripe direction. Rectangular patterns exhibited stress relief in orthogonal directions, and a 9 x 12 µm2 rectangle exhibited an average stress of 0.5 kbar. For as-grown GaAs/Si layers 0.9 to 3.25 µm thick, the stress is weakly dependent on layer thickness. For T > looK the stress in as-grown GaAs/Si is reduced and at 295K a value of 1.51 ± 0.21 kbar is obtained. With patterned growth, using a native SiO2 mask, no reduction in stress was observed irrespective of the pattern size, indicating the importance of free GaAs edges in obtaining stress relief.