Heterojunction and superlattice detectors for infrared to ultraviolet

Abstract

The interest in Infrared and Ultraviolet detectors has increased immensely due to the emergence of important applications over a wide range of activities. Detectors based on free carrier absorption known as Hetero-junction Interfacial Workfunction Internal Photoemission (HEIWIP) detectors and variations of these heterojunction structures to be used as intervalence band detectors for a wide wavelength region are presented. Although this internal photoemission concept is valid for all semiconductor materials systems, using a well studied III-V system of GaAs/Al x Ga 1−x As to cover a wide wavelength range from UV to far-infrared (THz) is an important development in detector technology. Using the intervalence band (heavy hole, light hole and split off) transitions for high operating temperature detection of mid Infrared radiation is also discussed. A promising new way to extend the detection wavelength threshold beyond the standard threshold connected with the energy gap in a GaAs/Al x Ga 1−x As system is also presented. Superlattice detector technology, which is another promising detector architecture, can be optimized using both Type I and Type II heterostructures. Here the focus will be on Type II Strained Layer (T2SL) Superlattice detectors. T2SL Superlattices based on InAs/(In,GA)Sb have made significant improvements demonstrating focal plane arrays operating around 80K and with multiple band detection capability. A novel spectroscopic method to evaluate the band offsets of both heterojunction and superlattice detectors is also discussed.

Broadband and photovoltaic THz/IR response in the GaAs-based ratchet photodetector

“…2D , a large number of holes can be injected into the absorber because the graded barrier is greatly tilted and bent. The holes injected into the absorber are hot holes because they have excess energy of more than 120 meV, which is higher compared to the indigenous cold holes in the absorber ( 37 , 38 ). The energy transfer mechanism between the hot and cold holes occurs during the relaxation process of the hot holes.…”

Six‐arm Stellat Dendritic‐PbS Flexible Infrared Photodetector for Intelligent Healthcare Monitoring

“…Traditional commercial IR photodetectors based on III-V compound semiconductors, such as InGaAs and InGaAsP photodetectors, are not widely available due to the potentially high cost and complexity of materials and preparation techniques. [12][13][14][15][16][17] Moreover, it is challenging to apply the traditional III-V semiconductor epitaxy growth method to flexible sensors. IVA group metal sulfides have attracted increasing attention in the field of IR light detection due to their unique spatial structure, electronic structure, and flexible substrate compatibility.…”

Recent Progress on Extended Wavelength and Split-Off Band Heterostructure Infrared Detectors

“…The heterojunction detectors offer wavelength flexibility [29][30][31][32][33] and multicolor capability in these regions. The wavelength range includes short-wave infrared (SWIR) of 1-3 µm [29], mid-wave infrared (MWIR) of 3-5 µm [30], long-wave infrared (LWIR) of 5-14 µm [33], very-long-wave infrared (VLWIR) of 14-30 µm [32], far-wave infrared (FWIR) of 30-100 µm or 3-10 THz [31] and so on. Among these wavelength ranges of IR radiations, 3-5 [34] and 8-14 µm [35] are considered the atmospheric windows and are suitable for IR applications.…”