InAs-Sb/GaSb type-II strain compensated superlattices (SLS) are currently being used in mid-wave and long-wave infrared photodetectors. The electronic bandstructure of InSb and GaSb shows very strong anisotropy and non-parabolicity close to the Γ-point for the conduction band (CB) minimum and the valence band (VB) maximum. Particularly around the energy range of 45–80 meV from band-edge we observe strong non-parabolicity in the CB and light hole VB. The band-edge dispersion determines the electrical properties of a material. When the bulk materials are combined to form a superlattice we need a model of bandstructure which takes into account the full bandstructure details of the constituents and also the strong interaction between the conduction band of InAs and valence bands of GaSb. There can also be contact potentials near the interface between two dissimilar superlattices which will not be captured unless a full bandstructure calculation is done. In this study, we have done a calculation using second nearest neighbor tight binding model in order to accurately reproduce the effective masses. The calculation of mini-band structure is done by finding the wavefunctions within one SL period subject to Bloch boundary conditions ψ(L)=ψ(0)eikL. We demonstrate in this paper how a calculation of carrier concentration as a function of the position of the Fermi level (EF) within bandgap(Eg) should be done in order to take into account the full bandstructure of broken-bandgap material systems. This calculation is key for determining electron transport particularly when we have an interface between two dissimilar superlattices.

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A novel computational technique is presented to study the terminal influence inside the three-dimensional (3D) nano-scale metal-oxide semiconductor field effect transistor (MOSFET) using TCAD simulations. Within the MOSFET the derivative of the electrostatic potential with respect to voltages at each terminal is taken, and when these derivatives are summed together they always sum to unity. It is found that these functions can be used to quantify the relative influence or control of the terminals anywhere inside the MOSFET, including the channel. The motivation for moving from planar MOSFETs to 3D-MOSFETs is to increase the gate control over the channel. The terminal influence functions quantify the notion of control. To gain insight into the working of a semiconductor device, different quantities like potential, charge or current density etc. may be visualised. These quantities are available in the standard TCAD tool-kit. However, these do not directly address the mechanism of terminal control. The terminal response or control functions can be used to do this very clearly.

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