Enhancing the performance of surface-textured Ge Schottky photodetectors using the electroless chemical etching method

We employed a technique to enhance the performance of Ge Schottky photodetectors (PDs), namely using an electroless chemical etching method to create an antireflective surface. This method was effective and is simple and inexpensive. The texturing process reduced the average reflection loss of Ge surfaces to approximately 10% in the 1010–1690 nm range of incident wavelengths. The optoelectrical characteristics of Ge Schottky PDs with different texturing times were compared with those of non-textured Ge Schottky PDs. As the texturing time increased, the reflectance gradually decreased, leading to improved device performance in terms of photoresponsivity, quantum efficiency, and specific detectivity across the entire measured wavelength range (1010–1690 nm). At biasing of −3 V and under illumination of 1550 nm incident light, the Ge Schottky PD with surface texturing of over 50 min achieved responsivity and quantum efficiency of over 0.8 A/W and 65%, respectively. The device exhibited a linear relationship between the incident power and photocurrent with a slope value close to unity, indicating ideal device performance for surface-textured Ge Schottky PDs. This finding suggested that Ge Schottky PDs with surface texturing fabricated by using electroless chemical etching could be competitive candidates for near-infrared optoelectronics in the future.