Edson Gomes Camargo

High-Sensitivity Temperature Measurement With Miniaturized InSb Mid-IR Sensor

This paper reports the development and evaluation of an InSb photovoltaic infrared sensor (InSb PVS) operating at room temperature. The InSb PVS consists of 700 InSb p⁺ - p^- - n⁺ photodiodes connected in series, on a semi-insulating GaAs (100) substrate. An Al_0.17rIn_0.83Sb barrier layer between p⁺ and p^- layers was used to reduce diffusion of photo-excited electrons. Cutoff wavelength was 6.8 mum and output signal was almost linear with irradiance up to 0.6 mW/cm². Sensitivity of 67 muV/K and noise equivalent temperature difference of 2.2 mK/Hz^1/2 was obtained at room temperature, which shows the sensor to be a suitable for noncontact thermometry.

InSb Mid-Infrared Photon Detector for Room-Temperature Operation

We developed a small InSb mid-infrared (2–7 µm wavelength range) photon detector that operates at room temperature. The photodiode was made from (hetero epitaxial) InSb layers that were grown on a semi-insulating GaAs substrate by molecular beam epitaxy. To suppress the effects of the diffusion current of the p–i–n photodiode, we used an AlInSb barrier layer that raises the resistance of the photodiode. We also optimized the devices doping concentration and the infrared incidence window structure. These optimization steps realized high photoelectric current output in a room-temperature environment. We also increased the signal-to-noise ratio of the detector by connecting multiple photodiodes in series. The size of this detector is 1.9×2.7×0.4 mm3 and the detectivity is 2.8×108 cm Hz1/2/W at 300 K. This is a practical IR detector that can be used in general signal amplification ICs.

Miniaturized InSb photovoltaic infrared sensor operating at room temperature

This paper reports the development of a novel InSb photovoltaic infrared sensor (InSb PVS) operating at room temperature. The InSb PVS consists of an InSb p+/p-/n+ structure grown on semi-insulating GaAs (100) substrate, with a p+ Al0.17In0.83Sb barrier layer between p+ and p- layers to reduce diffusion of photo-excited electrons. Photodiodes were fabricated by wet etching process and, using a 500K blackbody, we obtained D* of 2.8x108 cmHz1/2/W and RV of 1.9 kV/W at room temperature. S/N was improved with the serial connection of 700 photodiodes patterned on a 600x600 μm2 chip. Increasing the number (N) of connected photodiodes, S/N ratio was improved by a factor of N1/2. RV was constant for signals ranging from DC to 500Hz. From spectral response measurements a cut-off wavelength of 6.8 μm was obtained. The InSb PVS was flip-chip bonded on a pre-amplifier IC, allowing the shortest connection between the InSb PVS and the pre-amplifier, making the system immune to electromagnetic noise. The system was finally encapsulated by a Dual Flat Non-leaded (DFN) package with a window, which exposes the backside of the GaAs substrate allowing the infrared light incidence. The device external sizes are 2.2 mm x 2.7 mm x 0.7 mm and to our knowledge is the smallest uncooled sensor for the middle-infrared range reported until now.

A Novel InSb Photodiode Infrared Sensor Operating at Room Temperature

A microchip-sized InSb photodiode based infrared sensor (InSb PDS) that operates at room temperature was developed. The InSb PDS consists of 700 photodiodes connected in series and consumes no power, because it works in photovoltaic mode to output an open-circuit voltage. The InSb PDS has a typical responsivity of 1,900 V/W and an output noise of 0.15 μV/Hz 1/2 . A detectivity of 2.8×10 8 cmHz 1/2 /W was obtained at 300 K. The InSb PDS has performance high enough for applications such as mobile electronic equipment, personal computers, and consumer electronics

Performance Improvement of Molecular Beam Epitaxy Grown InSb Photodiodes for Room Temperature Operation

In this paper, we report the optimization of the light absorber layer thickness of InSb p+–p-–n+ photodiodes grown by molecular beam epitaxy (MBE) on GaAs(001) substrates. An Al0.17In0.83Sb barrier layer between p+ and p- layers was used to reduce the diffusion of photoexcited electrons, allowing rectifying characteristics and high photovoltage response at room temperature. Photodiodes with a junction area of 90×90 µm2 and p--layer thicknesses varying from 0.5 to 3 µm were fabricated, demonstrating that photocurrent increased with p--layer thickness, which is in good agreement with theoretical calculations. However, the non biased differential resistance did not increase as expected, possibly owing to an increase in film defect density with increasing film thickness, which is considered to produce leakage paths through the light absorber layer. Despite the presence of defects on the grown films, photodiodes with a p--layer thickness of 3 µm showed a sixfold improvement in the signal-to-noise ratio when compared with that of 0.5 µm.

NDIR gas sensing using high performance AlInSb mid-infrared LEDs as light source

In this paper, we report the performance of room temperature operated mid-infrared light emitting diode (LED) with an InSb buffer layer and AlInSb active/barrier layers, which showed to be suitable for non-dispersive infrared (NDIR) gas sensing. Characterization of the LED was performed and we found that good carrier confinement and crystalline quality was responsible for its high performance. High efficiency light extraction was obtained by adopting backside emission architecture together with surface roughening treatment and TiO2 anti-reflection coating. The fabricated AlInSb LED showed 75% higher power conversion efficiency when compared with a commercially available device. The developed LED, together with a commercially available infrared (IR) detector equipped with band-pass optical filter (AK9710, manufactured by Asahi Kasei Microdevices) were coupled into a mirror system forming a light path length of 80 mm, which was tested for CO2 gas sensing. For a non-absorbing environment, sensor output of 8 nA was obtained by driving the LED with peak current of 100 mA and, by exposing the system at CO2 concentration of 1000 ppm signal reduction due to absorbance around 12% was obtained.

Miniaturized InSb Mid-JR Sensor for Room Temperature Operation

This paper reports the development and evaluation of an InSb photovoltaic infrared sensor (InSb PVS) operating at room temperature. The InSb PVS consists of 700 InSb p⁺-p^--n⁺ photodiodes connected in series, on a semi-insulating GaAs (100) substrate. An Al_0.17In_0.83Sb barrier layer between p⁺ and p^- layers was used to reduce diffusion of photo-excited electrons. Cutoff wavelength was 6.8 mum and output signal was linear with incident irradiance. Noise equivalent temperature difference (NETD) of 2.2times10^-3 degC/Hz^1/2 was obtained at room temperature, which shows the sensor to be a promising device for human body detection or non-contact thermometry.