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Dr Khalifa M Azizur-Rahman

Postdoctoral Research Associate, Research
Advanced Materials and Devices - Sêr Cymru Research Group

+44 (0)29 2251 0181
Room N/3.13, Queen's Buildings - North Building, 5 The Parade, Newport Road, Cardiff, CF24 3AA



High efficiency detection of single photons at telecommunication wavelengths (notably at 1.55 µm) is critical for emerging technologies, such as free-space and on-fiber quantum information processing, eye-safe and long-distance light detection and ranging (LiDAR), and highly sensitive remote sensing. This research project aimed to meet this critical need by developing III-V nanopillar-based uncooled single-photon avalanche diodes (NP-SPADs).


1.T-Y Chang, H Kim, W A Hubbard, K M Azizur-Rahman, J J Ju, J-H Kim, W-J Lee, D L Huffaker, “InAsP Quantum Dot-Embedded InP Nanowire toward Silicon Photonic Application,” ACS Appl. Mater. Interfaces, 2022. [Supplementary Cover article]

2.Y Ji, K M Azizur-Rahman, T Chang, B-C Juang, D L Prout, B Liang, D L Huffaker, A F Chatziioannou, “Optimization of surface passivation for suppressing leakage current in GaSb PIN devices,” Electronics Letters, 56 (25), 2020.

3.D Ren, K M Azizur-Rahman, Z Rong, B-C Juang, S Somasundaram, A C Farrell, B S Williams, and D L Huffaker, “Developing uncooled InAsSb nanowire photodetector arrays with Al2O3 passivation for photodetection at mid-wavelength infrared,” Nano Lett., 19 (5), 2019. [Supplementary Cover article]

4.A C Farrell, X Meng, D Ren, H Kim, P Senanayake, N Y Hseih, Z Rong, T-Y Chang, K M Azizur-Rahman, and D L Huffaker, “InGaAs-GaAs nanowire avalanche photodiodes toward single photon detection in free-running mode,” Nano Lett., 19 (1), 2018.

5.D Ren, Z Rong, K M Azizur-Rahman, S Somasundaram, and D L Huffaker, “Feasibility of achieving high detectivity at short- and mid-wavelength infrared using nanowire photodetectors with p-n heterojunctions,” Nanotechnology, 30 (4), 2018.

6.D Ren, X Meng, Z Rong, M Cao, A C Farrell, S Somasundaram, K M Azizur-Rahman, B S Williams, and D L Huffaker, “Uncooled photodetector at short-wavelength infrared using InAs nanowire photoabsorbers on InP with p-n heterojunctions,” Nano Lett., 18 (12), 2018.

7.D Ren, Z Rong, S Somasundaram, K M Azizur-Rahman, B Liang, and D L Huffaker, “A three-dimensional insight into correlation between carrier lifetime and surface recombination velocity for nanowires,” Nanotechnology, 29 (50), 2018.

8.M Robson, K M Azizur-Rahman, D Parent, P Wojdylo, D A Thompson, and R R LaPierre, “Multispectral absorptance from large-diameter InAsSb nanowire arrays in a single epitaxial growth on silicon,” Nano Futures, 1 (3), 1 – 7, 2017.

9.R R LaPierre, M Robson, K M Azizur-Rahman, and P Kuyanov, “A review of III-V nanowire infrared photodetectors and sensors,” Journal of Physics D: Applied Physics, 50 (12), 1 – 10, 2017.

10.K M Azizur-Rahman and R R LaPierre, “Optical design of a mid-wavelength infrared InSb nanowire photodetector,” Nanotechnology, 27 (31), 1 – 8, 2016.

11.K M Azizur-Rahman and R R LaPierre, “Wavelength-selective absorptance in GaAs, InP, and InAs nanowire arrays,” Nanotechnology, 26 (29), 1 – 7, 2015. [Cover article]

12.A H Trojnar, C E Valdivia, K M Azizur-Rahman, R R LaPierre, K Hinzer, and J J Krich, “Optimization of GaAs nanowire solar cell efficiency via optoelectronic modeling,” IEEE 42nd PVSC, 1 – 6, 2015.

13.R R LaPierre, A C E Chia, S J Gibson, C M Haapamaki, J Boulanger, R Yee, P Kuyanov, J Zhang, N Tajik, N Jewell, and K M A Rahman, “III–V nanowire photovoltaics: Review of design for high efficiency,” Phys. Status Solidi – Rapid Res. Lett., 7 (10), 815 – 830, 2013. [Cover article]






Project Implementation Summary:

The project was implemented through 5 different experimental and simulation work packages (WPs). In:

*WP1: bottom-up p-n GaAs and p-i-n InGaAs nanopillars and InGaAsP/InP planar thin films for top-down etch were grown.
*WP2: fabrication process was optimized using p-n GaAs nanopillar and then the optimized fabrication process was used for fabricating p-i-n InGaAs nanopillar devices.
*WP3: both p-n GaAs and p-i-n InGaAs were characterized for I-V (room temperature and low temperature) and C-V (approximate doping). Photocurrent was also measured for p-i-n InGaAs nanopillars.
*WP4: preliminary Gm-APD model for planar SAM-APD structure was developed and ex-situ PECVD nitride (SiNx) passivation was investigated on InGaAs nanopillars and a simulation model was developed. Lastly,
*WP5: p-i-n InGaAs nanopillar devices were bonded to chips and top down etched InP and InGaAsP/InP nanopillars were fabricated, further photoluminescence study was carried out to investigate their surface quality following digital etching.

The dissemination of the project will continue even after the official end date with scientific papers in various stages of preparation to be published soon.

Progress beyond the state of the art:

We pushed the state of the art in bottom-up and top-down nanopillar device fabrication. We investigated ex-situ nanopillar passivation and surface passivation model. We also investigated ensemble p-n GaAs nanopillar devices. We have also paved the foundation for top-down etched InGaAsP/InP nanopillar devices. These results will no doubt open new areas of investigation into III-V nanopillar devices.

Technical Press Coverage

1.John Wallace, LaserFocusWorld, “Short- and mid-wavelength infrared nanowire photodiodes are uncooled,” June 14, 2019, website link:
2.ACS Publications, Highlight of a Supplementary Cover Article published in Nano Letters, June 10, 2019, website link:
3.D Ren & K M Azizur-Rahman, Compound Semiconductor, “UCLA And Cardiff Team Deliver Uncooled Nanowire SWIR/MWIR Detectors,” May 29, 2019, website link:
4.D Ren & K M Azizur-Rahman, Sensor Solutions, “UCLA And Cardiff team deliver uncooled nanowire SWIR/MWIR detectors” May 29, 2019, website link: detectors 
5.B Dumé, “New infrared camera goes multi-spectral,” November 06, 2017, website link: