Abstract
This thesis is on the preparation of Al2O3 thin films on InSb substrate by atomic layer deposition (ALD) using trimethyl-aluminum as the metal precursor. Two different surface pre-treatments are introduced before Al2O3 deposition: TMA/Ar pulse and chemical etching with CP4A. The cleaning effects of three pre-treatments to form well-defined interface are demonstrated. Chemical compounds retained at the interface after the different cleaning process are identified by XPS and an in-situ cleaning mechanism based on a ligand exchange reaction is proposed.Then, the electrical properties of Al2O3 film deposited on InSb with different surface condition are studied. The J-Vg relation exhibits the good insulator property (~10-8 to 10-7 A/cm2 within ±4V) and the C-V characteristics at 77k reveal the satisfactory performance of the MOS structure. An improvement of the electrical properties from the cleaning treatments is clearly demonstrated. Rapid thermal annealing (RTA) before metallization was also carried out in this work, but the electrical properties become degraded which is attributed to the generation of interface states by the RTA treatment.