Band Structure of GaP1-xNx(x= 0.25, 0.5, 0.75) Ordered Alloys: Semiempirical Tight-Binding Calculation

Abstract

A semiempirical tight-binding calculation of the electronic structure of GaP1-xNx ordered alloys (x=0.25, 0.5, and 0.75) has been performed. The bowing parameter of the band gap is extremely large (7.6 and 3.2 eV for the \\varGamma–X and the \\varGamma–\\varGamma transitions, respectively), which explains the experimental band gap reduction with increasing x when x<0.03 as observed by photoluminescence (PL) measurements [S. Miyoshi, H. Yaguchi, K. Onabe, R. Ito and Y. Shiraki: Appl. Phys. Lett. 63 (1993) 3506]. We have clarified that the large bowing originates from the large valence band (VB) offset between GaP and GaN (3.66 eV by Harrison's rule). The calculated band lineup of the GaP1-xNx alloy indicates that not only the GaP1-xNx–GaP heterojunction but also the GaP1-xNx–GaN heterojunction will show a type-II transition. The electronic structures of GaAs1-xPx and GaAs1-xSbx ordered alloys have also been calculated, and the values were consistent with the experimental band gap. The consistency confirms the validity of our calculation. The calculation is also applied to the electronic structure of a GaAs1-xNx ordered alloy (x=0.25, 0.5, and 0.75) which is also found to have large bowing parameters (4.0, 8.5, and 6.2 eV for the \\varGamma–\\varGamma, \\varGamma–X, and \\varGamma–L transitions, respectively) probably due to the large VB offset between GaAs and GaN.