Influence of growth temperatures on the quality of InGaAs/GaAs quantum well structure grown on Ge substrate by molecular beam epitaxy

Molecular beam epitaxy growth of an In;Ga;As/GaAs quantum well（QW） structure（x equals to 0.17 or 0.3） on offcut（100） Ge substrate has been investigated.The samples were characterized by atomic force microscopy,photoluminescence（PL）,and high resolution transmission electron microscopy.High temperature annealing of the Ge substrate is necessary to grow GaAs buffer layer without anti-phase domains.During the subsequent growth of the GaAs buffer layer and an In;Ga;As/GaAs QW structure,temperature plays a key role. The mechanism by which temperature influences the material quality is discussed.High quality In;Ga;As/GaAs QW structure samples on Ge substrate with high PL intensity,narrow PL linewidth and flat surface morphology have been achieved by optimizing growth temperatures.Our results show promising device applications forⅢ-Ⅴcompound semiconductor materials grown on Ge substrates.

Comparative studies of Ge and Si p-channel metal-oxide-semiconductor field-effect-transistors with HfSiON dielectric and TaN metal gate

Ge and Si p-channel metal-oxide-semiconductor field-effect-transistors （p-MOSFETs） with hafnium silicon oxynitride （HfSiON） gate dielectric and tantalum nitride （TAN） metal gate are fabricated. Self-isolated ring-type transistor structures with two masks are employed. W/TaN metal stacks are used as gate electrode and shadow masks of source/drain implantation separately. Capacitance-voltage curve hysteresis of Ge metal-oxide-semiconductor （MOS） capacitors may be caused by charge trapping centres in GeOx （1 〈 x 〈 2）. Effective hole mobilities of Ge and Si transistors are extracted by using a channel conductance method. The peak hole mobilities of Si and Ge transistors are 33.4 cm2/（V.s） and 81.0 cm2/（V.s）, respectively. Ge transistor has a hole mobility 2.4 times higher than that of Si control sample.