Al 2 O 3 films, 200 ran thick, were chemically vapor deposited on (100) silicon substrates by hydrolysis of AlCl 3 at 900°C in a H 2 ‐rich atmosphere of H 2 and CO 2 Heat‐treatment in H 2 atmosphere produces no change in the charge state of the oxide. Heat‐treatment in O 2 N 2 or Ar atmospheres produces only a redistribution of the negative charge grown in during deposition. Heat‐treatment in H 2 subsequent to that in O 2 N 2 or Ar restores the original charge distribution. The flatband voltage characterizing these shifts approached a constant value with time (10V). The temperature dependence of the rate of approach to saturation is consistent with first‐order kinetics and an activation energy of 1.42 eV. These results and the effects of annealing on optically active charge trapping centers are interpreted in terms of a simple phenomeno logical model. It is suggested that the charge trapping centers are due to a hydrogen‐related species formed during film deposition.
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Mehta et al. (1973) studied this question.