Analysis of crosstalk in HgCdTe p-on-n heterojunction photovoltaic infrared sensing arrays

Abstract

In this paper, an experimental and theoretical study is carried out of crosstalk between nearest-neighbor devices within a backside-illuminated linear HgCdTe photovoltaic infrared sensing array. The dominant form of crosstalk that occurs in high performance photovoltaic arrays is associated with photogenerated minority carriers that diffuse laterally between adjacent devices within the array. To measure crosstalk, a scanning laser microscope is used to obtain a spatial map of spot-scan photoresponse at a temperature of 80K for individual p-on-n photovoltaic devices within the linear array. These experimental results are compared to calculations performed on a commercial two-dimensional device simulation package. The crosstalk measurements and calculations presented in this paper include results on mid-wavelength infrared planar device structures, as well as long-wavelength infrared mesa-isolated devices, which give measured crosstalk values of 6.2 and 8.3%, respectively. The results indicate that the device simulations are in good agreement with experimental results. Further simulations are carried out to determine the sensitivity of crosstalk to various material and device parameters such as epitaxial layer thickness (7 to 25 µm), illumination wavelength (1.047 to 11.0 µm), minority carrier diffusion length (8 to 90 µm), and diode pitch. It is found that the dominant feature influencing the value of crosstalk is the distance between the region of photogeneration and the collecting p-n junction.

Optimization of Microlenses for InSb Infrared Focal-Plane Arrays

“…Finally, the photoresponse curve from pixel 2 is obtained. At the same time, crosstalk, which is defined as the pixel 1 response divided by the pixel 2 response as a percentage, 9 can be evaluated by computing the photocurrent at the contacts. Figures 2 and 3 show the simulated response and crosstalk characteristics of the photodetectors with 47.2-lm-, 52.2-lm-, and 57.2-lm-thick n-type InSb layers using the configurations shown in Fig.…”

The characteristic analysis and optimization design for HgCdTe TDI infrared detector array

“…•Electronic-crosstalk attributes to the process that the carriers generated by photons in the nominal collection region of a particular element of a photosensitive array diffuse and are collected by other elements [10,12] .…”

“…Generally speaking, the Electronic-Crosstalk is dominant in photosensitive array. Therefore, when crosstalk is measured the overall crosstalk is obtained [9,10] . To accurately measure and calculate the optic-crosstalk, a small optic-spot within the spot size of 2 μm need to be used.…”

“…While the diode size increases, it is expected that the crosstalk will decrease, when the diode material parameters, such as diffusion length, device structure parameters and semiconductor epitaxial layer thickness, are invariant [10] . When the center distance of detector is a constant, the relationship between E-CT and the width of diode is equal to the relationship between E-CT and the edge distance between two adjacent diodes.…”

Determination of the Bulk and Local Diffusion-Length Values of Charge Carriers in MCT Films and in the Absorber Layers of MCT-Based Photovoltaic IR FPA Detectors

“…With known mobility of minority carriers, this knowledge also permits evaluation of the lifetime of excess carriers in MCT, which is often hard to measure because of its small value. Finally, the length l d is generally regarded as a key parameter that defines the crosstalk value of FPA detectors [5][6][7][8][9].…”