Structural control of In 2 Se 3 polycrystalline thin films was attempted by molecular beam epitaxy (MBE) technique. In 2 Se 3 polycrystalline films were obtained on glass substrates at substrate temperatures above 400°C. VI/III ratio greatly affected crystal structure of In 2 Se 3 polycrystalline films. Mixtures of α-In 2 Se 3 and γ-In 2 Se 3 were obtained at VI/III ratios greater than 20, and layered InSe polycrystalline films were formed at VI/III ratios below 1. γ-In 2 Se 3 polycrystalline thin films without α-phase were successfully deposited with VI/III ratios in a range of 2 to 4. Photocurrent spectra of the γ-In 2 Se 3 polycrystalline films showed an abrupt increase at approximately 1.9 eV, which almost corresponds with the reported bandgap of γ-In 2 Se 3 . Dark conductivity and photoconductivity measured under solar simulator light (AM 1.5, 100 mW/cm 2 ) were approximately 10 -9 and 10 -5 S/cm in the γ-In 2 Se 3 polycrystalline thin films, respectively.

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Boron nitride (BN) films with a high cubic phase content have been synthesized. The films are deposited by reactive sputtering of a pure boron target in electron cyclotron resonance (ECR) plasmas and ion bombardment to a substrate is enhanced by rf biassing of the substrate. A cubic phase of BN is grown over a certain threshold value of ion bombardment energy. The threshold and the cubic phase content depend on the ratio of ion flux to boron atom flux to the substrate. The threshold decreases as the ratio increases; however, the cubic phase content also decreases, particularly in a high ion flux region. BN films with a high cubic phase content show surface cracking and delamination because of the high compressive stress induced by ion bombardment. An intermediate hexagonal BN layer, of a certain thickness between layer with high cubic phase content and the substrate prevents surface cracking and improves film adhesion.

Cubic boron nitride (c-BN) thin films are synthesized by reactive sputtering. Pure boron is used as the sputtering target, which is dc-biassed in an Ar/N 2 electron cyclotron resonance plasma. Substrates are rf-biased with a frequency of 13.56 MHz. BN films with a dominant cubic phase are obtained in the case of a high ion-to-boron flux ratio of 12 at the substrate self-bias higher than −175 V; the transferred momentum per atom is about 1260 (eV amu) 1/2 , which is larger than the value predicted using the momentum transfer model for c-BN synthesis by a factor of 4. An intermediate layer between the c-BN layer and the substrate improves the adhesion of the c-BN layer and prevent a exfoliation. This intermediate layer is deposited under an Ar/N 2 gas mixing ratio of 9 without rf bias.

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