2018年6月25日星期一

Hot wall epitaxy of Sb2Te3 layers: coherent hetero-epitaxy on InAs(1 1 1) and Sb substitution in Cu-mediated growth

The growth of Sb2Te3 layers by means of hot wall epitaxy is investigated. While the layers grow coherently on InAs(1 1 1) substrates owing to the small lattice mismatch, the appropriate substrate temperature is restricted to a narrow range and the surface preparations play a critical role for the growth due to the rapid re-evaporation of Sb2Te3. We also examine the growth on various substrates having a pre-deposited Cu layer. The Cu layer retains Sb2Te3 at the surface and thus extends the usable substrate-temperature range. During the substitution of the Sb atoms with the Cu atoms, we encounter an incorporation of the group-III elements to the grown layers when III–V compounds are used as the substrates. We additionally present the low-temperature magnetotransport properties in a layer synthesized by the substitution.

Source:IOPscience

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2018年6月5日星期二

A New High Electron Mobility Transistor (HEMT) Structure with a Narrow Quantum Well Formed by Inserting a Few Monolayers in the Channel

A new HEMT wafer has been developed whose channel layer has a narrow bandgap semiconductor with a few monolayers inserted at an optimum position in the channel, namely, the point where the probability density of electrons is maximum in the lowest subband and negligible in the first excited subband. The Al0.22Ga0.78As/In0.15Ga0.85As pseudomorphic HEMT wafer with one InAs monolayer inserted at the optimum position has provided Hall electron mobility increments nearly 15% higher at 300 K and 20% higher at 77 K than those of conventional pseudomorphic HEMT wafers.


Source:IOPscience

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