Atomic layer deposition of Al2O3 thin films on diamond

Atomic layer deposition (ALD) of aluminum oxide thin films on diamond was demonstrated for the first time, and the film properties as a gate insulator for diamond field effect transistor (FET) were examined. The interface between the aluminum oxide and the diamond was abrupt, and the ratio of aluminum to oxygen in the film was confirmed to be stoichiometric by Rutherford back scattering. Even a bumpy surface of polycrystalline diamond film was conformally covered by the Al2O3 films. To evaluate the feasibility of the film for FET gate insulator, the electrical characteristics of the Al2O3 films deposited by ALD on diamond were measured using metal–insulator–semiconductor structure. It was found that the Al2O3 films deposited by ALD were better than those deposited by conventional methods, which indicates that the ALD-Al2O3 films are feasible for gate insulators of diamond FETs.