Typically, photodetectors require an external voltage to provide the driving force for separating and measuring photo-generated electrons that comprise the detection.
To eliminate this need, the research team developed a stable photodetector based on a semiconducting junction called a GdNiO3/Nb-doped SrTiO3 (GNO/NSTO) p-n heterojunction.
An inherent electric field at the GNO/NSTO interface is said to provide the driving force for efficient separation of photo-generated carriers, eliminating the need for an external power source.
In addition to its self-powered feature, the team claims to have tuned the material’s properties to achieve broad sensitivity.
"Our work is novel and confirms that perovskite nickelates films have tuneable band gaps with changing of the oxygen vacancy concentration, which makes them suitable as light absorbing materials in optoelectronic devices," said lead author Le Wang.
According to the researchers, a challenge in developing the photodetector was determining the correct band structure, or energy structure available to electrons, of the 10nm thick GNO films.
"To obtain the band structures, we used both spectroscopic ellipsometry measurements and ultraviolet photoelectron spectroscopy measurements," said Wang.
The team hopes to explore more materials with similar features. They also plan to improve the performance of the photodetector by adding an insulating SrTiO3 layer sandwiched between the GdNiO3 film and NSTO substrate.
