Anand Singh

High Performance of Midwave Infrared HgCdTe e-Avalanche Photodiode Detector

This letter reports on the design and fabrication of HgCdTe electron-avalanche photodiode (e-APD) for low dark current and high gain for imaging applications. HgCdTe e-APD photodiodes were fabricated in the n+-ν-p+ configuration for FPA at 30 μm × 30 μm pitch. Process for creating the required carrier profile and compositional grading in the absorption and multiplication regions was developed. Graded bandgap profile in the absorption region has been introduced. Shallow mesa etch isolation and effective passivation of side walls were introduced to control lateral currents. High quantum efficiency of 65% makes these APDs suitable for applications like quantum encryption. These measures helped in achieving high avalanche gain of 5550 at 8 V reverse bias in HgCdTe MWIR e-APD for the first time.

Performance of Graded Bandgap HgCdTe Avalanche Photodiode

This paper reports the performance of midwave infrared (MWIR) electron-injection avalanche photodiode (e-APD) fabricated using graded bandgap HgCdTe epilayers. Carrier transport in the e-APD is dominated by drift transport due to the built-in electric field associated with gradient in the bandgap. Carriers encounter fewer collision events before entering the multiplication region as the dead space effect is reduced. On-set of generation and multiplication processes is controlledmore effectively. High gain indicates a reduced in-elastic scattering by phonon-emission due to gradient. Quantum efficiency above 80% is achieved in merely 2–3-

HgCdTe e-avalanche photodiode detector arrays

\mu \text{m}

HgCdTe avalanche photodiodes: A review

-thick absorbing layer because of more efficient collection of the photogenerated carriers. Lower generation volume is beneficial in terms of low dark current. The generation is confined in the vicinity of themultiplication region. Generated carriers are readily evacuated from the absorber region under the built-in electric field. An order of magnitude improvement over the state-of-the art performance in MWIR e-APD is achieved by introducing a controlled energy bandgap gradient in the HgCdTe epilayers.

Carbon Nanotube–Purification and Sorting Protocols

Initial results on the MWIR e-APD detector arrays with 30 μm pitch fabricated on LPE grown compositionally graded p-HgCdTe epilayers are presented. High dynamic resistance times active area (R0A) product 2 × 106 Ω-cm2, low dark current density 4 nA/cm2 and high gain 5500 at -8 V were achieved in the n+-υ-p+ HgCdTe e-APD at 80 K. LPE based HgCdTe e-APD development makes this technology amenable for adoption in the foundries established for the conventional HgCdTe photovoltaic detector arrays without any additional investment.