The growth characteristics during metalorganic chemical vapor deposition and optical properties of ZnO films on sapphire （Al2O3） （0001） and （1120） substrates are studied. For the former,the effects of two import...The growth characteristics during metalorganic chemical vapor deposition and optical properties of ZnO films on sapphire （Al2O3） （0001） and （1120） substrates are studied. For the former,the effects of two important growth parameters,i, e. temperature and pressure, are investigated in detail. Due to the large lattice mismatch between the film and the substrate, ZnO nanocrystals are usually obtained. The growth behavior at the film-substrate interface is found to be strongly dependent on the growth temperature,while the growth pressure determines the shape of the nanostructures as they grow. It is difficult to obtain ZnO films that have good quality and a smooth surface simultaneously. Due to the smaller lattice mismatch,the critical thickness of ZnO on the Al2O3 （1120） surface is found to be much larger than that on the Al2O3 （0001） surface. ZnO/MgZnO quantum wells with graded well thicknesses are grown on the Al2O3 （1120） surfaces,and their optical properties are studied. The built-in electric field in the well layer, generated by the piezoelectric effect, is estimated to be 3 × 10^5 V/cm. It is found that growth at low temperatures and low pressures may facilitate the incorporation of acceptor impurities in ZnO.展开更多
A novel substrate current model is proposed for submicron and deep-submicron li ghtly-doped-drain (LDD) n-MOSFET,with the emphasis on accurate description of the characteristics length by taking the effects of channe...A novel substrate current model is proposed for submicron and deep-submicron li ghtly-doped-drain (LDD) n-MOSFET,with the emphasis on accurate description of the characteristics length by taking the effects of channel length and bias int o account.This is due to that the characteristics lenth significantly affects th e maximum lateral electric field and the length of velocity saturation region,bo th of which are very important in modeling the drain current and the substrate c urrent.The comparison between simulations and experiments shows a good predictio n of the model for submicron and deep-submicron LDD MOSFET.Moreover,the analyti cal model is suitable for descgn of devices as it is low in computation consumpt ion.展开更多
文摘The growth characteristics during metalorganic chemical vapor deposition and optical properties of ZnO films on sapphire （Al2O3） （0001） and （1120） substrates are studied. For the former,the effects of two important growth parameters,i, e. temperature and pressure, are investigated in detail. Due to the large lattice mismatch between the film and the substrate, ZnO nanocrystals are usually obtained. The growth behavior at the film-substrate interface is found to be strongly dependent on the growth temperature,while the growth pressure determines the shape of the nanostructures as they grow. It is difficult to obtain ZnO films that have good quality and a smooth surface simultaneously. Due to the smaller lattice mismatch,the critical thickness of ZnO on the Al2O3 （1120） surface is found to be much larger than that on the Al2O3 （0001） surface. ZnO/MgZnO quantum wells with graded well thicknesses are grown on the Al2O3 （1120） surfaces,and their optical properties are studied. The built-in electric field in the well layer, generated by the piezoelectric effect, is estimated to be 3 × 10^5 V/cm. It is found that growth at low temperatures and low pressures may facilitate the incorporation of acceptor impurities in ZnO.
文摘A novel substrate current model is proposed for submicron and deep-submicron li ghtly-doped-drain (LDD) n-MOSFET,with the emphasis on accurate description of the characteristics length by taking the effects of channel length and bias int o account.This is due to that the characteristics lenth significantly affects th e maximum lateral electric field and the length of velocity saturation region,bo th of which are very important in modeling the drain current and the substrate c urrent.The comparison between simulations and experiments shows a good predictio n of the model for submicron and deep-submicron LDD MOSFET.Moreover,the analyti cal model is suitable for descgn of devices as it is low in computation consumpt ion.
