Efficient light absorption is the most crucial factor for high spectral responsive photodetection phenomenon. Nanopillars for photodetection constitute a great opportunity in enhancing the light absorption efficiency along with reducing the electrical cross-section of the device. Here an analytical investigation of a proposed periodic GaAs material based half octagonal cut based vertically oriented hexagonal nanopillar array deployed over a 5um x 5um front detector’s surface has been done for attaining an optimum light absorbance by reducing the surface reflectivity of the incoming photons. The geometrical analysis of the proposed model exhibits a 0.999 absorbance and 0.97A/W photoresponsivity along with 86% EQE at 1um operating wavelength.