Jinchao Tong

Study of dual color infrared photodetection from n-GaSb/n-InAsSb heterostructures

We report detailed investigation of n-GaSb/n-InAsSb heterostructure photodetectors for infrared photodetection at different temperatures and biases. Our results show that the heterostructure photodetectors are capable of dual color photodetections at a fixed forward bias with its highest responsivity occurred at room temperature; With the decrease of the forward bias, a turning point, at which the photocurrent changes its direction, exist and the corresponding voltage values increases with the decrease of temperature; At all reverse biases, the photocurrents flow in the same direction but the maximum current occurs at about 205 K. A new model is proposed, which can well explain all the observations.

Surface plasmon induced direct detection of long wavelength photons

Millimeter and terahertz wave photodetectors have long been of great interest due to a wide range of applications, but they still face challenges in detection performance. Here, we propose a new strategy for the direct detection of millimeter and terahertz wave photons based on localized surface-plasmon-polariton (SPP)-induced non-equilibrium electrons in antenna-assisted subwavelength ohmic metal–semiconductor–metal (OMSM) structures. The subwavelength OMSM structure is used to convert the absorbed photons into localized SPPs, which then induce non-equilibrium electrons in the structure, while the antenna increases the number of photons coupled into the OMSM structure. When the structure is biased and illuminated, the unidirectional flow of the SPP-induced non-equilibrium electrons forms a photocurrent. The energy of the detected photons is determined by the structure rather than the band gap of the semiconductor. The detection scheme is confirmed by simulation and experimental results from the devices, made of gold and InSb, and a room temperature noise equivalent power (NEP) of 1.5 × 10−13 W Hz−1/2 is achieved.The detection of terahertz and millimeter waves has many applications, but there are still limitations in their technical performance. Here, Tong et al. demonstrate the direct detection of long-wavelength radiation through surface plasmon excitation and a corresponding improvement in detection performance.

Aluminum based structures for manipulating short visible wavelength in-plane surface plasmon polariton propagation

We report aluminum based structures for manipulation of surface plasmon polariton (SPP) propagation at short wavelength range. Our simulation shows that aluminum is a good metal to excite and propagate SPPs with blue light and that the SPP wavelength can be reduced from about 465 nm to about 265 nm by monitoring the thickness of a coated Si(3)N(4) layer above the aluminum film. It is also shown that the damping becomes more significant with the increase of the thickness of the Si(3)N(4) layer. We also experimentally demonstrated the SPP wavelength tuning effect for 20nm Si(3)N(4) layer covered Al, which can be explained by the variation of effective permittivity. The proposed Metal-Insulator-Air (MIA) structures with SPP wavelength tuning ability have potential applications in 2D optics.

InAs0.91Sb0.09 photoconductor for near and middle infrared photodetection

Antimonide based III–V materials have been attracting great attention as they have wide applications covering photodetection, light source, photovoltaics and electronic devices. In this paper, we report on the structural and optical properties and photodetection performance of an InAsSb layer grown on a GaSb substrate by molecular beam epitaxy (MBE). An x-Ray diffraction (XRD) study shows that the Lattice-mismatch between the GaSb substrate and the InAsSb epitaxial layer is about 0.17% and the derived composition of Sb is about 0.09. Photoluminescence measurements at varied temperatures reveal that the energy band gap of the InAsSb material is about 0.33 eV and the luminescence peaks follow Bose–Einstein relation. The photoconductors fabricated based on the InAsSb/GaSb structure show spectral response ranging from NIR to MWIR range. They can work well at low voltage bias and the measured blackbody detectivitives are ~2.4 × 107 cmHz1/2W−1 and ~6.1 × 109 cmHz1/2W−1 at room temperature and 77 K, respectively.

Single Plasmonic Structure Enhanced Dual-band Room Temperature Infrared Photodetection

Dual-band photodetection in mid- and near-wave infrared spectral bands is of scientific interest and technological importance. Most of the state-of-the-art mid-infrared photodetectors normally operate at low temperature and/or suffer from toxicity and high cost due to limitations of material properties and device structures. The capability of surface plasmons in confining electromagnetic waves into extremely small volume provides an opportunity for improving the performance for room temperature operation. Here, we report an n-InAsSb/n-GaSb heterostructure photodiode integrated with plasmonic two-dimensional subwavelength hole array (2DSHA) for room temperature two band photodetection. We demonstrate that with a properly designed 2DSHA, room temperature detectivities of the heterostructure device can be enhanced to ~1.4 × 109 Jones and ~1.5 × 1011 Jones for the two bands peaked at 3.4 μm and 1.7 μm, respectively. In addition, we study the photocurrent enhancement in both photoconductor and heterojunction modes in the same integrated structure. The demonstration of single 2DSHA enhanced heterojunction photodiode brings a step closer to high sensitivity room temperature devices and systems which require multiband absorption.

Room temperature plasmon-enhanced InAs0.91Sb0.09-based heterojunction n-i-p mid-wave infrared photodetector

Middle wavelength infrared (MWIR) photodetectors have a wide range of applications, but almost all of them operate at low temperature due to the limit of materials and device structures. The capability of plasmonic structures to localize electromagnetic wave on the deep subwavelength scale provides the possibility for MWIR photodetectors operating at room temperature. Here, we report a high sensitivity room temperature MWIR photodetector which is an InAs0.91Sb0.09-based heterojunction n-i-p photodiode integrated with a Au-based two-dimensional subwavelength hole array (2DSHA). A room temperature detectivity of 0.8 × 1010 cm Hz1/2 W−1 and a response time of 600 ns are achieved. The non-cooling high performance of 2DSHA-InAs0.91Sb0.09 based heterojunction photodetectors will make their applications easier, broader, and economic.

Antimonide-based semiconductors for optoelectronic devices

We report high quality InAsSb films grown on Ge substrates with a GaAs intermediate layer via metal-organic chemical vapor deposition. The properties of the grown InAsSb films are systematically analysed. It is found that the grown InAsSb films by this method have high quality with very smooth, mirror-like morphology, and high optical quality. In particular, strong PL peak at around 3550 nm can be observed even at room temperature, which demonstrates the capabilities of the grown InAsSb films for room temperature MIR optoelectronic application. This work provides a simple and feasible strategy for the growth of high quality InAsSb films on Ge substrate.