Lateral bipolar photoresistance effect in the CIGS heterojunction and its application in position sensitive detector and memory device

Cu(In,Ga)Se₂ (CIGS) based multilayer heterojunction, as one of the best high efficiency thin film solar cells, has attracted great interest due to its outstanding features. However, the present studies are primarily focused on the structure optimization and modulation in order to enhance the photoelectric conversion efficiency. Here, we exploit another application of this multilayer heterostructure in photoresistance-modulated position sensitive detector by introducing lateral photoresistance effect. The lateral photoresistance measurements show that this multilayer heterojunction exhibits a wide spectral response (~330 to ~1150 nm) and excellent bipolar photoresistance performances (position sensitivity of ~63.26 Ω/mm and nonlinearity <4.5%), and a fast response speed (rise and fall time of ~14.46 and ~14.42 ms, respectively). More importantly, based on the lateral photoresistance effect, the CIGS heterostructure may also be developed as a position-dependent resistance memory device, which can be modulated by changing laser intensity, wavelength, and bias voltage with excellent stability and repeatability, and the position resolution reaches up to 1 μm. These results can be well explained by considering the diffusion and the drift model of carriers in the CIGS multilayer heterojunction. This work provides a new approach of achieving novel photoelectric sensors and memory devices based on the traditional photovoltaic heterostructures.