Quantum confinement in group III–V semiconductor 2D nanostructures

Band gap variation in group III–V semiconductor slabs due to quantum size effects.

Strain Distributions in Group IV and III-V Semiconductor Quantum Dots

A theoretical model was developed using Green’s function with an anisotropic elastic tensor to study the strain distribution in and around three dimensional semiconductor pyramidal quantum dots formed from group IV and III-V material systems namely, Ge on Si, InAs on GaAs and InP on AlP. A larger positive strain in normal direction which tends to zero beyond 6nm was observed for all three types while the strains parallel to the substrate were negative. For all the three types of quantum dots hydrostatic strain and biaxial strain along x and z directions were not linear but described a curve with a maximum positive value near the base of the quantum dot. The hydrostatic strain in x-direction is mostly confined within the quantum dot and practically goes to zero outside the edges of the quantum dot. For all the three types, the maximum hydrostatic and biaxial strains occur in x-direction around -1nm and around 2nm in z-direction. The negative strain in x-direction although realtively weak penetrate more deeper to the substrate than hydrostatic strain.The group IV substrate gave larger hydrostatic and biaxial strains than the group III-V semiconductor combinations and InAs /GaAs was the most stable. The results indicated that the movements of atoms due to the lattice mismatch were strong for group III-V.

Electron Scattering in Buried InGaAs MOSFET Channel with HfO2 Gate Oxide

Group III-V semiconductor materials are being studied as potential replacements for conventional CMOS technology due to their better electron transport properties. However, the excess scattering of carriers in MOSFET channel due to high-k gate oxide interface significantly depreciates the benefits of III-V high-mobility channel materials. We present results on Hall electron mobility of buried QW structures influenced by remote scattering due to InGaAs/HfO2 interface. Mobility in In0.77Ga0.23As QWs degraded from 12000 to 1200 cm2/V-s and the mobility vs. temperature slope changed from T-1.2 to almost T+1.0 in 77-300 K range when the barrier thickness is reduced from 50 to 0 nm. This mobility change is attributed to remote Coulomb scattering due to charges and dipoles at semiconductor/oxide interface. Elimination of the InGaAs/HfO2 interface via introduction of SiOx interface layer formed by oxidation of thin a-Si passivation layer was found to improve the channel mobility. The mobility vs. sheet carrier density shows the maximum close to 2×1012 cm-2.