We report a top-down approach based on atomic force microscopy (AFM) local anodic oxidation for the fabrication of the nano-pattern field effect transistors (FETs). AFM anodic oxidation is relatively a simple process in atmosphere at room temperature but it still can result in patterns with a high spatial resolution, and compatibility with conventional silicon CMOS process. In this work, we study nano-pattern FETs for various cross-bar distance value D, from ${sim}0.5;{mu}m$ to $1;{mu}m$. We compare the optical characteristics of the patterned FETs and of the reference FETs based on both 2-dimensional simulation and experimental results for the wavelength from 100 nm to 900 nm. The simulated the drain current of the nano-patterned FETs shows significantly higher value incident the reference FETs from ${sim}1.7;{ imes};10^{-6}A$ to ${sim}2.3;{ imes};10^{-6}A$ in the infrared range. The fabricated surface texturing of photo-transistors may be applied for high-efficiency photovoltaic devices.