Admittance of metal–insulator–semiconductor devices based on HgCdTe nBn structures

Abstract

Metal-insulator-semiconductor (MIS) structures were fabricated by depositing an Al 2 O 3 dielectric on top of the contact layer of a mid-wave infrared nBn detector based on n-Hg 1-x Cd x Te grown by molecular beam epitaxy on GaAs (013) substrates. It is shown that when creating a backward electrode on the absorbing layer, the form of the capacitance-voltage characteristics depends not only on the properties of the contact layer, but also on the properties of the barrier and absorbing layers. An equivalent circuit of MIS structure based on nBn detector with mesa configuration is proposed. It is shown that measurements of the admittance of MIS structures with mesa configuration allow one to study the properties of the barrier layer in the nBn structure. The influence of infrared radiation on the temperature dependence of the barrier layer resistance is studied.

Comprehensive experimental study of NBνN barrier structures based on n-HgCdTe MBE for detection in MWIR and LWIR spectra

“…Broader studies of the electrophysical properties can be carried out in the fabrication of structures based on the investigated heterostructures of the metal-insulator-semiconductor (MIS) type. Measurements of the admittance of barrier structures in the MIS configuration, carried out in a wide range of temperatures, frequencies, and biases, make it possible to determine additional parameters of multilayer unipolar systems and reveal the features of the processes occurring in such systems [26,27].…”

Admittance of MIS Structures Based on nBn Systems of Epitaxial HgCdTe for Detection in the 3–5 μm Spectral Range

“…The creation of efficient nBn detectors with parameters providing the maximum detectivity requires detailed studies of the electrical properties of unipolar multilayer HgCdTe systems. One of the methods for studying the electrical properties of various layers in nBn systems is to measure the admittance of such systems [9,10] or metalinsulator-semiconductor (MIS) structures on their basis [11,12]. The aim of this work is to study in a wide range of conditions the admittance of MIS structures based on an nBn system from MBE HgCdTe with layer parameters close to optimal for creating efficient MWIR detectors.…”

“…where ReZ and ImZ are the real and imaginary parts of the impedance, respectively. The main expressions allowing one to describe the admittance (or impedance) of an MIS structure based on an nBn system are given in [11].…”

“…In this circuit, R d and C d are the resistance and capacitance of the dielectric layer and R b and C b are the resistance and capacitance of the barrier layer. The total EC should also include series resistance of the bulk of the absorbing layer R bulk [11,12], but, for the sample under study, the presence of this resistance can be neglected in a wide range of conditions (due to the small nominal value of this resistance). The lines in Fig.…”

Aдмиттанс МДП-структур на основе nBn-систем из эпитаксиального HgCdTe, разработанных для детектирования в спектральном диапазоне 3-5 μm

“…Для создания эффективных nBn-детекторов с параметрами, способными обеспечить максимальные значения обнаружительной способности, необходимы детальные исследования электрических свойств униполярных многослойных систем на основе HgCdTe. Одним из способов исследования электрических свойств различных слоев в nBn-системах являются измерения адмиттанса таких систем [9,10] или МДП-структур (МДП -металл−диэлектрик−полупроводник) на их основе [11,12]. Цель настоящей работы -исследование в широком диапазоне условий адмиттанса МДП-структур на основе nBn-системы из МЛЭ HgCdTe с параметрами слоев, близкими к оптимальным для создания эффективных MWIR-детекторов.…”