Electronic Structure and Optical Gain of InNBiAs/InP Pyramidal Quantum Dots

Dilute bismide alloys and dilute nitride alloys have garnered increasing research interest over the past few years, as it promises increased engineering flexibility in the design of advanced compound semiconductor heterostructure devices. Key device parameters such as lattice constant, bandgap and band offsets can be controlled with greater precision, and this leads to better performance for a wide range of electronic and optoelectronic devices. For dilute nitride alloys, band anticrossing effects are produced due to the coupling of their resonant states with the conduction band states. This lowers the conduction band edge energy. Likewise, the coupling of the resonant states of dilute bismide with the valence band states results in the valence band anticrossing and the valence band edge energy rises. Additionally, the effective bandgap may fall below the spin-orbital-splitting energy, thus inhibiting Auger recombination. This makes them excellent candidates for optoelectronic device applications. In this work, the electronic bandstructure and optical gain of InNBiAs/InP pyramidal quantum dots are investigated using the 16-band k·p model with constant strain. The effective bandgap falls as we increase the composition of nitrogen and bismuth. With an appropriate choice of composition of doped atoms, we can tune the emission wavelength in the range of 2–5µm suitable for mid-infrared device applications. Additionally, we observe the size effect by tuning the size of quantum dot.