Investigation of the electronic properties, first and second harmonic generation for AXIIIBXV zinc-blende semiconductors

We present the results of the ab initio theoretical study of the electronic properties, first and second harmonic generation for AlP, AlAs, AlSb compounds with zinc-blende structure performed using the full-potential linearized-augmented plane wave (FP-LAPW) method. The results for the band structure, density of states, and the frequency-dependent linear and nonlinear optical response are present here. Our calculations show that these compounds have similar electronic structures. The valence band maximum (VBM) is located around Γ and the conduction band minimum (CBM) is located around X resulting in an indirect energy band gap. The energy band gap of these compounds decreases when P is replaced by As and As by Sb. This can be attributed to the increases in bandwidth of the conduction bands when moving from P to As to Sb in agreement with the experimental data and previous theoretical calculations. The linear and nonlinear optical spectra are analyzed and the origin of some of the peaks in the spectra is discussed in terms of the calculated electronic structure. We find that the intra- and inter-band contributions of the second harmonic generation show insignificant increases when we move from P to As, while it shows significant increases when we move from As to Sb. The smaller energy band gap compounds have larger values of χ123(2)(0), in agreement with the experimental measurements and other theoretical calculations.