STRUCTURE AND PROPERTIES OF Ⅲ-N SEMICONDUCTOR THIN FILMS GROWN AT LOW TEMPERATURES BY N-RADICAL-ASSISTED PULSED LASER DEPOSITION

摘要

Thin films of nitride semiconductors are usually grown by means requiring high substrate temperatures. Deposition techniques providing higher kinetic energies of incident species offer an alternative route which might allow growth of good quality films at lower temperatures. Pulsed Laser Deposition can provide higher kinetic energies than most thin film growth methods. However, Ill-nitride thin films grown by PLD are often nitrogen deficient. We have been able to obtain good stoichiometry for aluminum nitride films even at room temperature by providing atomic nitrogen at low (thermal) energies during growth. Very good orientation can be obtained on (001) sapphire substrates at moderate temperatures (～ 500 C). A1N films were grown from either A1N or Al targets. We also report on preliminary work by the same method with GaN film growth from a liquid Ga target.