Antimony based III-V Semiconductors

Antimony (Sb) containing III-V semiconductors have bandgaps ranging from 1.6 eV (AlSb) down to 0.17 eV (InSb). Therefore, III-Sb alloys can cover a broad range of energies in the near and mid infrared regions of the electromagnetic spectrum and are of interest for infrared detectors [1,2] and gas sensing emitters [3]. In particular this material system shows promise for light-detection and ranging (LiDAR) detectors used in autonomous vehicles [4].

Challenge
The growth of Sb-containing semiconductors is significantly less mature compared to the established systems of III-As and III-P. The challenges to growth of high-quality structures include the high segregation length of Sb, control of strong elemental exchanges between Sb and other group V elements, accommodation of lattice mismatch between antimonides and the other III-V semiconductors and a miscibility gap in ternary/quaternary alloys.

Figure: TEM image of an InAs/GaSb type-II superlattice

Solution
At the EPSRC National Epitaxy Facility we have been developing antimony containing materials since the late 1990s and have attained extensive expertise in tackling the above-mentioned crystal growth challenges.

Our work includes various Sb-containing semiconductor structures, from bulk homojunction pin diodes to type-II superlattice photodetectors and intra-band cascade lasers. The complex nature of these superlattices is illustrated in the transmission electron microscopy (TEM) image shown in the figure.

Key factors allowing the National Epitaxy Facility to have a leading position in this field are:
– An MBE reactor equipped with the latest Sb cracker cell allowing a wide range of III-V-Sb combinations and an MOVPE reactor with Sb-containing metalorganics.
– Established calibration procedures for key growth parameters ensuring reproducibility and continuous improvement.
– The availability of in-house electrical, optical and structural characterisation facilities.
– Close and collaborative working with customers to gain quick feedback and to develop the field.

Notable achievements from the National Epitaxy Facility include:

• World-class Near- and Mid-Infrared super lattice photodetectors with type II staggered band alignment (InGaAs/GaAsSb SLs on InP, InAs/GaSb SLs on GaSb).
• State-of-the-art Quantum Cascade Lasers based on antimonide alloy layers for improved carrier confinement.
• InAs quantum dots with Sb surfactants and dilute nitrides. Improved optical quality was achieved at telecom bands (1.2-1.6 microns).
• InSb/AlInSb two-dimensional electron gas (2DEG) structures on GaAs with high room temperature mobility.

We welcome the opportunity to work with you in new areas of antimonide-based structures built on this expertise.

References

[1] – Smith, D. L., and C. Mailhiot. “Proposal for strained type II superlattice infrared detectors.” Journal of applied Physics 62.6 (1987): 2545-2548.
[2] – Rogalski, A., P. Martyniuk, and Ma?gorzata Kopytko. “InAs/GaSb type-II superlattice infrared detectors: Future prospect.” Applied physics reviews 4.3 (2017): 031304.
[3] – Gaimard, Q. et al., (2015). Distributed feedback GaSb based laser diodes with buried grating: a new field of single-frequency sources from 2 to 3 µm for gas sensing applications. Optics express, 23(15), 19118-19128.
[4] – Lee, Seunghyun, et al. “High gain, low noise 1550 nm GaAsSb/AlGaAsSb avalanche photodiodes.” Optica 10.2 (2023): 147-154.