Phase selective growth of rhombohedral and cubic indium oxide polytypes was studied. The selective growth of different polytypes was achieved by adjusting substrate temperature and trimethylindium flow rate during metal organic chemical vapor deposition on c-plane sapphire. The optical band gaps of the cubic and rhombohedral phases were determined to be ∼3.7 and ∼3.0eV, respectively. On the basis of the performed structural investigations, a phenomenological model of the nucleation and growth of highly textured cubic In2O3 on Al2O3 (0001) is proposed.
A room temperature ozone induced oxidation of thin InN films is proposed to improve the electric transport properties. The sheet carrier density is reduced upon oxidation by a value which is in the order of the electron concentration of an untreated InN surface. Thus, ozone effectively passivates the surface defect states on InN and might be an effective method to prepare InN films for electronic applications. A model for the improved electron transport properties is proposed taking into account the decreased surface band bending and the decreased influence of surface electrons on the net mobility of InN layers.
Aluminum and nickel contacts were prepared by evaporation on sulfur-passivated n-and p-type Si͑100͒ substrates. The Schottky diodes were characterized by current-voltage, capacitance-voltage, and activation-energy measurements. Due to the passivation of Si dangling bonds by S, surface states are reduced to a great extent and Schottky barriers formed by Al and Ni on Si͑100͒ substrates show greater sensitivity to their respective work functions. Aluminum, a low work function metal, shows a barrier height of Ͻ0.11 eV on S-passivated n-type Si͑100͒ and ϳ0.80 eV on S-passivated p-type Si͑100͒, as compared to 0.56 and ϳ0.66 eV for nonpassivated n-and p-type Si͑100͒, respectively. Nickel, a high work function metal, shows ϳ0.72 and ϳ0.51 eV on S-passivated n and p-type Si͑100͒, respectively, as compared to ϳ0.61 and ϳ0.54 eV on nonpassivated n and p-type Si͑100͒, respectively. Though a surface dipole forms due to the adsorption of S on Si͑100͒, our experimental results indicate that the effect of surface states is the dominant factor in controlling the Schottky barrier height in these metal-Si systems.
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