A versatile photodetector assisted by photovoltaic and bolometric effects

The advent of low-dimensional materials with peculiar structure and superb band properties provides a new canonical form for the development of photodetectors. However, the limited exploitation of basic properties makes it difficult for devices to stand out. Here, we demonstrate a hybrid heterostructure with ultrathin vanadium dioxide film and molybdenum ditelluride nanoflake. Vanadium dioxide is a classical semiconductor with a narrow bandgap, a high temperature coefficient of resistance, and phase transformation. Molybdenum ditelluride, a typical two-dimensional material, is often used to construct optoelectronic devices. The heterostructure can realize three different functional modes: (i) the p–n junction exhibits ultrasensitive detection (450 nm–2 μm) with a dark current down to 0.2 pA and a response time of 17 μs, (ii) the Schottky junction works stably under extreme conditions such as a high temperature of 400 K, and (iii) the bolometer shows ultrabroad spectrum detection exceeding 10 μm. The flexible switching between the three modes makes the heterostructure a potential candidate for next-generation photodetectors from visible to longwave infrared radiation (LWIR). This type of photodetector combines versatile detection modes, shedding light on the hybrid application of novel and traditional materials, and is a prototype of advanced optoelectronic devices. Optoelectronics: lighting the way to advanced photodetectors Scientists from China have made photodetectors from semiconducting and two-dimensional materials that could lay the foundations for advanced optoelectronic devices. Photodetectors made from two-dimensional semiconducting materials such as quantum dots, nanowires, nanoflakes, and nanofilms have led to smaller devices that exhibit ultrafast response times, exceptional sensitivity, or a broad-spectrum response compared to devices made from traditional materials. Currently, however, no device can combine all these attributes. A team of Chinese researchers led by Jianlu Wang from the Shanghai Institute of Technical Physics has now developed a hybrid photodetector made from an ultrathin film of vanadium dioxide and a molybdenum telluride nanoflake. The photodetector combines a rapid response with high sensitivity and is capable of detecting visible to longwave infrared radiation, paving the way for better-performing devices for use in a range of optoelectronic applications.