Effect of degree of strain relaxation on polarization charges of GaN/InGaN/GaN hexagonal and triangular nanowire solar cells

Abstract

The innovative contribution of this paper is to derive polarization charges in hexagonal and triangular GaN/InGaN/GaN core/shell/shell nanowire solar cells considering effect of degree of strain relaxation (R) and appropriate stiffness coefficients. The crystal orientation angle, φ and non-linear effect of spontaneous polarization are tailored with strain calculations for a better precision of polarization charges in nanowire type devices. The article also formulated the effect of polarization charges while InGaN layers are grown above or below GaN layer in both types of nanowires depending on the lattice expansion or compression. The model accounts an innovative concept of polarization charges distribution with respect to growth of crystal orientation and strain relaxation. It is observed that nanowire solar cell with triangular geometry could be good enough for efficient generation of power as compared to hexagonal nanowire solar cell. This concept of one triangular nanowire solar cell exhibits an efficiency of 3.18% with 90.34% fill factor under 1 Sun AM1.5 illumination with 20% ‘In’ composition.