Interband cascade infrared photodetectors with enhanced electron barriers and p-type superlattice absorbers

Abstract

We present results on the optical and electrical performance of mid-infrared detectors based on interband-cascade structures. These devices include enhanced electron barriers, designed to suppress intraband-tunneling current between stages, and p-doped type-II InAs/GaSb superlattice absorbers. Within the sample set, we examined devices with different absorber thicknesses and doping levels. Carriers are extracted less efficiently in devices with longer absorbers, which is attributed to more band bending within the absorber due to electric charge accumulation. Also, devices with lower-doped (1 × 1017 cm−3) absorbers are found to have better optical and electrical performances than those with higher levels of doping (3 × 1017 cm−3). The overall performance of these devices was superior to previously reported results, with Johnson-noise limited detectivities, at 4.0 μm, as high as 6.0 × 1012 and 2.5 × 1011 Jones at 80 and 150 K, respectively.

Growth And Characterization Studies Of Advanced Infrared Heterostructures

“…In our design, a type-II broken-gap band alignment between the hB and eB is adopted. Such a design facilitates a fast carrier relaxation path for photo-generated electrons, leading to efficient collection of photo-generated carriers [9][10]. As schematically shown in Fig.…”

“…1. The first is the absorber region in which photo-excited carriers are generated, the second is a hole barrier (hB) that allows transport through electron relaxation and the third is an electron barrier (eB) that enables tunneling into the next stage [10]. The hB typically consists of coupled multi-quantum wells (MQWs), such that a series of staircase energy ladders is formed in the conduction band.…”

“…For the past several years, T2SL technology has received considerable amount of scientific and technological interest. Owing to the great flexibility/versatility of energy band alignment in the nearly lattice-matched "6.1-Å-family" (InAs, GaSb, AlSb, and their alloys) [2], and reduced Auger recombination rate and heavier electron effective masses, various advanced T2SL-based photodetector architectures have been implemented, leading to significantly improved detector performances [3][4][5][6][7][8][9][10]. Among them are the double heterostructures with graded-gap W-structure [3] and M-structure [4], as well as unipolar-barrier detectors [5][6], complementary-barrier IR detectors [7], and interband cascade IR photodetectors (ICIPs) [8][9][10].…”

HOT infrared photodetectors

“…Recently has been appeared that for near−room tempera− ture detector operation more promising are bipolar devices based on type−II InAs/GaSb interband (IB) supperlattice (SL) absorbers [59][60][61][62][63]. These interband cascade detectors combine the advantages of interband optical transitions with the excellent carrier transport properties of the interband cascade laser structures.…”

“…28 [61]. The detector consists of a 0.5 μm p−type GaSb buffer layer, then a 7−stage interband cascade structure using a finite InAs/GaSb type−II SL (T2SL) as an absorber, and finally a 45−nm−thick n−type InAs top contact layer.…”