Bandgap tunable Al1-In N films for ultraviolet–visible photodetectors with wide spectral response

Al1-xInxN films allow the bandgap to be adjusted in a wide range, which is fascinating for optoelectronic applications, especially in ultraviolet–visible and wavelength-selective photodetection. Herein, the single-phase Al1-xInxN films with tunable bandgap are synthesized via a well-designed radio-frequency (RF) magnetron sputtering method. By means of placing an In sheet on the Al target, we can control the Al and In composition in Al1-xInxN films via only changing the RF power on the target. With increasing the RF power from 100 to 300 W, the In composition (x value) in Al1-xInxN films can be adjusted from 0.94 to 0.34. Accordingly, the bandgaps are adjusted from 2.20 to 2.95 eV. Importantly, the photoresponse wavelengths of Al1-xInxN films are broadened from UV to visible light with raising the x value. The photoresponsivity of the Al1-xInxN film photodetectors is 0.0124 mA/W (x = 0.34), 0.118 mA/W (x = 0.52), and 0.126 mA/W (x = 0.67) under 365 nm, 532 nm, and 650 nm illumination, respectively. The corresponding response times are as fast as 2.37 s, 1.98 s, and 1.39 s, respectively. Our synthesis strategy of Al1-xInxN films proposed in this work will open exciting opportunities for semiconductor bandgap adjustment and wavelength-selective detection of optoelectronic devices.