LAUSR

We present a combination of X-ray photoelectron spectroscopy (XPS) and time-resolved photoluminescence (TRPL) to probe the details of interface formation between CdTe and alumina deposited by atomic layer deposition (ALD). Alumina ALD using water as the oxygen source causes the elimination of Te oxides that are initially present on air-exposed CdTe surfaces. TRPL on the resulting CdTe interface indicates some degree of passivation. On the other hand, postgrowth treatment of Al2O3/CdTe structures with CdCl2 and oxygen causes regrowth of Te oxides. Some of these structures show improved lifetimes, thereby pointing toward a critical role for Te oxides in interfacial CdTe passivation by Al2O3. Direct measurement of band positions with XPS indicates that the passivation is caused primarily by chemical rather than field effect mechanisms.