Ultraviolet (UV) photodetectors have recently drawn enormous research interest due to their wide range of applications in civil, military, and biological fields. However, low sensitivity and complex fabrication processes are hindering their full potentials. To take the advantages of wideband and direct bandgap properties of AlGaN and GaN, this study demonstrates a simple one-mask fabrication technique to fabricate AlGaN/GaN 2DEG based photodetectors. The sensitivity of the detector is found to be as high as 1.58×104 A/W under the illumination of 365 nm and 8.2×10-8 W/cm2 at 10 V. The structure also exhibited an excellent sensitivity with deep UV (254 nm) illuminations. The observed characteristics of the proposed heterostructure have been explained in detail via an energy band diagram analysis.