Laser induced disordering of GaAs-AlGaAs superlattice and incorporation of Si impurity

Abstract

A scanned Ar⁺ laser beam is demonstrated to be an effective way to selectively disorder very localized regions of an AlGaAs‐GaAs superlattice. As the focused laser beam scans across the sample, the superlattice rapidly melts and then regrows. Scanning electron microscope images of the scan cross section show a micron‐sized region of nearly homogeneous composition with a sharp (<400 Å) transition to as‐grown superlattice material. In addition, dopants such as Si deposited on the surface in an encapsulation layer are incorporated into the melt in high concentrations during the scanning process. In this way, the recrystallized material can serve as a patterned source for impurity induced disordering during a standard thermal anneal. The depth and width of the disordered region are given as a function of laser power measured before and after the thermal anneal (850 °C, 6 h).