The results of an electrical study of the damage caused by the Ar-ion beam etching of molecular beam epitaxially grown Si-doped AlxGa1-xAs laser diode material were reported. This involved measurements of the capacitance as a function of voltage and temperature, as well as deep-level transient spectroscopy measurements of Schottky-barrier diodes. The Schottky contacts were fabricated by depositing Au in a vacuum onto the etched AlGaAs surface. As a control, Schottky diodes of the best quality were produced in situ by evaporating Al onto the top of the epilayer at the end of the molecular beam epitaxy growth run. On the basis of a comparative study, deep-level defects related to the sub-surface damaged layer were identified. Emission signatures as well as depth profiles of the defect concentration were analyzed. Deep-level transient spectra also revealed the presence of a well-known DX(Si) center and a M-type defect related level which was attributed to a vacancy and impurity complex. The presence of an additional deep-level defect located in the lower half of the energy gap, that was induced by dry etching, was also suggested. The extra defect had a sufficiently high concentration to disturb carrier spatial profiles and DX-center characteristics. It was suggested that it could be responsible for degradation effects in GaAs/AlGaAs heterostructure lasers whose fabrication involved dry etching.

Deep-Level Defects Induced by Ar-Ion Beam Etching in n-Type AlxGa1-xAs Grown by MBE. M.Kaniewska, J.Bozek: Crystal Research and Technology, 2003, 38[3-5], 351-8