LTMBE GAAS - PRESENT STATUS AND PERSPECTIVES

When GaAs is grown via MBE at 200 degrees C (compared to the normal 580-600 degrees C), the films manifest a remarkable set of structural, electrical and optical properties. As grown, LT GaAs (as it is commonly known) has an excess of As, contains a high concentration of point defects, displays hopping band conductivity and shows little, if any, photoluminescence. After a 600 degrees C anneal, the layers have a relaxed lattice constant, are highly resistive and contain a distribution of As precipitates. The point defect concentration diminishes by several orders of magnitude. The photo-induced carrier lifetime typically is of the order of 200 fs. This account will review what is known about these interesting materials, discuss models to explain the transport properties and mention potential applications.