Phase transitions in Ga-Sb phase change alloys

GaSb alloys are potential candidates for phase change random access memory (PCRAM) applications. GaSb alloys of variable compositions including the single stoichiometric GaSb and several Sb-rich compositions were studied using resistivity versus temperature measurements, static laser testing, and time-resolved X-ray diffraction. It was found that the stoichiometric alloy has an unusual inverse optical contrast compared to typical phase change materials as the crystalline phase has lower reflectance compared to the amorphous phase. Sb-rich alloys show a decrease in reflectance upon crystallization at lower temperature but an increase in reflectance at higher temperature from subsequent Sb segregation. Alloys very rich in Sb only show a positive change in reflectance upon crystallization typical for conventional phase change materials. Change in reflectance of a Ga/Sb?=?36:64 (in at.%) amorphous thin film crystallized by laser pulses of variable length and power. Unusual for a phase change material, this alloy shows both positive and negative contrast at different laser power levels.