Optical and electrical characterizations of laser–chemical-vapor-deposited aluminum oxynitride films

Abstract

Composition-dependent optical and electrical properties of (Al2O3)1−c-(AlN)c composite films (0≤c≤1) are investigated herein. The films are deposited by the laser-assisted, chemical-vapor-deposition (L-CVD) technique. Film composition is controlled by background vacuum level (e.g., O2) and substrate temperature. Optical parameters of the oxynitride films on quartz substrates are evaluated from spectrophotometric transmittance characteristics. Infrared absorption spectra are used to identify chemical composition of the films. Electrical-field-dependent current flow mechanisms are investigated for Al-insulator-n-Si metal-insulator-semiconductor (MIS) structures. Current-voltage (I-V) characteristics of the MIS structures exhibit two alternative states: the original and the programmed states. The original state I-V characteristics are obtained for virgin films by first application of the tracing voltage. Current density versus electric field follows both exp E and exp (E)1/2 regions. The MIS structure makes a transition from the original to a programmed state at high electric field due to the establishment of a persistent polarization field. Programmed MIS structures exhibit two alternative I-V characteristics corresponding to whether the applied and the polarization field are in the same or opposite directions. Capacitance-voltage (C-V) characteristics of L-CVD (Al2O3)1−c-(AlN)c devices exhibit composition-dependent hysteresis. A large clockwise hysteresis is observed for AlN while smaller size anticlockwise hysteresis is obtained for the Al2O3 case.