Articles you may be interested inEffect of NH3 plasma treatment on the interfacial property between ultrathin HfO2 and strained Si0.65Ge0.35 substrate J.Vacancy-impurity complexes in polycrystalline Si used as gate electrodes of HfSiON-based metal-oxidesemiconductors probed using monoenergetic positron beams

We have investigated influence of substrate polarity on the growth of InN films by RF-MBE. It was found that the temperature required for successful growth of InN strongly depended on the substrate polarity. InN could be grown on C-face SiC at 550 °C, whereas no InN growth occurred on Si-face SiC at 550 °C. InN growth on Si-face SiC was realized at lower temperature of 450 °C. In the case of the growth on freestanding GaN substrates, InN could be grown on N-face GaN at 550 °C, whereas InN growth on Ga-face GaN was realized at 450 °C. It was found that InN with N polarity can be grown at higher temperature than that with In polarity. These results indicate that control of polarity is essential for successful growth of InN.1 Introduction InN is a very attractive material for future optical and electronic devices due to its excellent physical properties. However, the growth of high-quality InN is very difficult, because of the low dissociation temperature of InN and the extremely high equilibrium vapour pressure of nitrogen. Therefore, physical properties of InN and its growth mechanism are still not fully understood. In the case of GaN growth, the polarity of GaN is a key characteristic because the film with Ga polarity has better surface morphology and crystal quality than the film with N polarity [1]. It is also reported that the decomposition rate of GaN is dependent on the polarity [2]. Furthermore, for GaN-based electronic devices using piezoelectric effect, the strain and the polar direction of the film influence device performances [3]. Thus, to understand and control the effect of the polarity is essential and many efforts have been made on these issues for GaN-related materials [4][5][6]. However, the number of reports on polarity of InN is only a few [7,8] and it is not understood how the polarity of substrate influences the growth of InN. In this paper, we investigate the influence of substrate polarity on growth of InN films.

InN films were grown on sapphire (0001) substrates by radio-frequency plasma-assisted molecular beam epitaxy. The InN buffer layers deposited at low temperature were either grown on a substrate with nitridation or on a substrate without nitridation. The InN buffer layers on the nitridated substrates were always single crystalline, whereas the buffer layers on non-nitridated substrates were always polycrystalline. However, even without nitridation process, single crystalline InN films could be grown on the polycrystalline InN buffer layers; in this case, the orientation was always [1120] InN//[1120] sapphire epitaxy, which differed from the [1010] InN//[1120] sapphire epitaxy in films grown with nitridation.

A case of language disorders owing to the presence of right cerebellar hemorrhage