Abstract
The methods of passivating the mesastructures of photodetectors based on InSb/In \({}_{1-x}\) Al \({}_{x}\) Sb nBn heterostructures grown by molecular-beam epitaxy are studied. The mesastructures are formed by photolithography and liquid etching. Two different dielectrics, Al \({}_{2}\) O \({}_{3}\) and Si \({}_{3}\) N \({}_{4}\) , are used to passivate the surface of mesastructures. It is shown that the Si \({}_{3}\) N \({}_{4}\) dielectric efficiently passivates the surface of mesastructures, and the bulk current channel is predominant, whereas the surface leakage current prevails in the Al \({}_{2}\) O \({}_{3}\) passivated mesastructures. At small reverse biases, the correlation between the current and surface area of a mesastructure is violated due to the influence of defects. Modeling the current–voltage characteristics of mesastructures at 77 K shows that the major contribution to the dark current is made by the tunneling current of electrons through the In \({}_{1-x}\) Al \({}_{x}\) Sb barrier.
