Optimization of a HOT LWIR HgCdTe Photodiode for Fast Response and High Detectivity in Zero-Bias Operation Mode

Abstract

Fast response is an important property of infrared detectors for many applications. Currently, high-temperature long-wavelength infrared HgCdTe heterostructure photodiodes exhibit subnanosecond time constants while operating under reverse bias. However, nonequilibrium devices exhibit excessive low-frequency 1/f noise that extends up to MHz range, representing a severe obstacle to their widespread application. Present efforts are focused on zero-bias operation of photodiodes. Unfortunately, the time constant of unbiased photodiodes is still at the level of several nanoseconds. We present herein a theoretical investigation of device design for improved response time and detectivity of long-wavelength infrared HgCdTe photodiodes operating at 230 K in zero-bias mode. The calculation results show that highly doped p-type HgCdTe is the absorber material of choice for fast photodiodes due to its high electron diffusion coefficient. The detectivity of such a device can also be optimized by using absorber doping of N A = 1 9 10 17 cm À3 . Reduction of the thickness is yet another approach to improve the device response. Time constant below 1 ns is achieved for an unbiased photodiode with absorber thickness below 4 lm. A tradeoff between the contradictory requirements of achieving high detectivity and fast response time is expected in an optically immersed photodiode with very small active area.

Bilayer graphene/HgCdTe based very long infrared photodetector with superior external quantum efficiency, responsivity, and detectivity

“…To the best of our knowledge, the obtained results for the proposed photodetector are better than that of previously reported graphene based photodetectors. 1,3,29,30,33,37,39,43,[82][83][84][85][93][94][95][96][97][98][99][100][101][102][103] Table 2 summarizes the key parameters of our proposed device with other MCT and graphene based photodetectors reported earlier.…”

Unipolar Semiconductor Barrier Structures for Infrared Photodetector Arrays (Review)

“…According to the calculations, the dark current in such HOT structures should be lower than in photodiodes with p-n junctions [38] and the performances at a specified temperature are better. At present, LWIR MOCVD HgCdTe-based HOT barrier structures containing p layers for high-speed detection with a single-element photodetector at a temperature of 230 K are being developed; a detectability value of 2 × 10 9 cm W -1 Hz 1/2 was obtained [6,39]. The development of HOT barrier structures for MBE HgCdTe-based photodetector arrays has not been reported in the literature yet.…”

Low frequency noise in reverse biased P-InAsSbP/n-InAs infrared photodiodes

“…In recent years the majority of low frequency noise (LFN) measurements were performed with HgCdTe [8][9][10][11] and PbS based detectors, including those using PbS colloidal quantum dots [12][13][14]. LFN in type-II InAs/GaSb superlattice PDs have also attracted considerable interest since they promise high background limited operation temperature [15][16][17][18].…”

“…On the other hand, experimental study of LFN in InAs-based heterostructure PDs have been performed only in [19] focusing mainly on forward bias regime. The lack of comprehensive LFN studies restricts the application areas of these promising devices [11].…”