Photovoltaic–Pyroelectric Coupled Effect in Ag2Se/Si Heterojunction for Broad-Band, Ultrafast, Self-Powered, Position-Sensitive Detectors

As a result of its high carrier mobility and peculiar phase transition, Ag2Se has been attracting increasing interest for applications that include thermoelectric power generation, solid electrolytes, and resistive random access memory devices. However, the narrow-band gap characteristics and excellent optoelectronic properties of the material are usually neglected or not used well. Here, we report on a simple Ag2Se/p-Si heterostructure position-sensitive detector (PSD) based on the lateral photovoltaic effect (LPE) and investigate the optoelectronic properties of this device for the first time. The broad-band performance, ultrafast response speed, and self-powered operation of the PSD are exploited, and the detector’s response performance is improved drastically by coupling of the photovoltaic and pyroelectric effects. A good linearity was observed for the laser position-dependent lateral photovoltage (LPV) response over a wide spectrum from the visible range to the near-infrared region. The effects of illumination power, laser wavelength, and switching frequency on the transient LPV response when modulated by the pyro-phototronic effect were investigated and discussed systematically, with an enhancement ratio of as large as 1797% being achieved. In addition, the response rise/fall times were reduced to 3/5 μs, respectively. The results presented here enable fundamental comprehension of the pyro-phototronic effect-based PSD and provide an accessible route toward the design and performance optimization of such a PSD.