Al/SiO2/p-Si structure with 4 nm SiO2 layer prepared by rapid thermal oxidation (RTO) technique at 950 degrees C/45 s condition was used as photodetector for visible and near infrared regions. The technical steps for fabrication process of NMOS device are given. I-V characteristics under dark and white light illumination are measured and analyzed. Breakdown of Si NMOS photodetector occurred at V-B = 12 V bias. The quantum efficiency (QE) of photodetector has a maximum value of 54% at lambda = 530 nm when the detector is biased to 4 V and is decreased to 20% at = 1000 nm. Neither grid gate transparent contacts nor antireflection coating have been used to enhance the QE of photodetector. Furthermore, these results are compared with published results. (c) 2007 Elsevier Ltd. All rights reserved.