The InSb epitaxial layer of p+-n-n+ structure was grown by Molecular Beam Epitaxy (MBE) on a heavily doped InSb substrate. Photodiodes of InSb were fabricated by standard semiconductor manufacturing process. Measurement and analysis of its electrical properties was carried out. Compared with traditional bulk crystal InSb of p+-n structure, we find that, when the external bias voltage is 0.1V, dark current density values of p+-n-n+ InSb device and InSb bulk material device is 1.1×10-6 A·cm-2 and 9.5×10-5 A·cm-2 at 77K, respectively. zero-bias-resistance area products is 8.9×104Ω·cm2 and 6.2×103 Ω·cm2 at 77K, respectively. Doping concentrations values in the absorption layers are equal to 5.0×1014 cm-3 and 1.3×1016 cm-3 , respectively. The InSb epitaxial layer of p+-n-n+ structure which has better crystal quality achieves better performance than bulk crystal InSb when the passivation process is reliable. It provides an important foundation for the fabrication of epitaxial InSb infrared detector.
Herein, we report a novel approach to passivation of InAs/GaSb superlattice for mid-short wavelength dual-color infrared detector. One of the major challenges faced by InAs/GaSb superlattice devices arises owing to the large number of surface states that are generated. Surface passivation and subsequent capping of the surfaces are absolutely essential for any practical applicability of this material system. As evidenced by the comparison of unpassivated and passivated InAs/ GaSb superlattice mid-short wavelength dual-color infrared photodiodes. The surface passivation methods include zinc sulfide (ZnS) coating after anodic oxide, and ZnS coating after fluoride passivation. InAs/GaSb superlattice infrared materials were grown by molecular beam epitaxy on GaSb (100) substrates. A GaSb buffer layer, which can decrease the occurrence of defects with similar pyramidal structure, was grown for optimized superlattice growth condition. The reliability of passivation by anodic fluoride was confirmed by AES. The leakage current as a function of bias voltage (J–V) for superlattice diodes obtained using different passivation methods has been examined at 77 K. The best performance was demonstrated by the ZnS after anodic fluoride passivation.
Infrared(IR)photo detectors based on InAs/GaSb type II superlattice have developed quickly in recent years. Many groups show great interest in InAs/GaSb superlattice detector for its superiors as high quantum efficient, high working temperature, high uniformity and low dark current densities. Inductively coupled plasma(ICP) etching of GaSb and InAs/ GaSb superlattices were performed using Cl2/Ar/CH4/H2. This paper introduceste inductively coupled plasma( ICP) etching of Inas/GaSb with SiO2 mask by the Cl2/Ar/CH4/H2 mixed-gas process. The effects of process parameters such as gas combination, ICP and RF power on the etch rate and quality of InAs/GaSb It is found that the ratio of Cl2 flow rate significantly affects the etch rate, due to the trade-off between physical and chemical component of etching. The etch rate of InAs/GaSb increases with the increase of percent of Cl2, there will InClx remains in the etching channel when the etching depth exceeded 2μm, which can stop the etching going on. This phenomenon can be eliminated by decrease the Cl2 ratio,to make sure the etching depth reach 6μm under a certain low etching rate. The surface morphology and SEM of the superlattice material after etching shows that dry etching morphology is better than wet etching.After the electrode is grown, the superlattice chip have a good diode characteristic curve.
Joule-Thomson coolers have been widely used in infrared photo-detector, which have their unique advantages with respect to compact, light and low cost. The performance of Joule-Thomson coolers is required to be improved with the development of higher mass and larger diameter focal plane infrared photo-detector. In order to maximize the usage time and minimize the cooling down time for a given volume of stored gas for Joule-Thomson coolers, it is important to study on fluid flow and heat transfer of Joule-Thomson coolers. Experiments and analysis are carried on to investigate the parameters of Joule-Thomson coolers. The effects of ambient temperatures are considered. It is useful to study the performance of Joule-Thomson coolers for large diameter focal plane infrared photo-detector. Deep research on Joule-Thomson coolers will be helpful to explore optimization of the Joule-Thomson coolers for infrared photo-detectors.
A high temperature operation mid-wavelength 128×128 infrared focal plane arrays (FPA) based on low Al component In1-xAlxSb was presented in this work. InAlSb materials were grown on InSb (100) substrates using MBE technology, which was confirmed by XRD and AFM analyses. We have designed and grown two structures with and without barrier. The pixel of the detector had a conventional PIN structure with a size of 50μmx50μm. The device fabrication process consisted of mesa etching, passivation, metallization and flip-chip hybridization with readout integrated circuit (ROIC), epoxy backfill, lap and polish. Diode resistance, imaging, NETD and operability results are presented for a progression of structures that reduce the diode leakage current as the temperature is raised above 80K. These include addition of a thin region of InAlSb to reduce p-contact leakage current, and construction of the whole device from InAlSb to reduce thermal generation in the active region of the detector. An increase in temperature to 110K, whilst maintaining full 80K performance, is achieved. The I-V curves were measured at different temperature. Quantum efficiency, pixel operability, non-uniformity, and the mean NETD values of the FPAs were measured at 110K. This gives the prospect of significant benefits for the cooling systems, including, for example, use of argon in Joule-Thomson coolers or an increase in the life and/or decrease in the cost, power consumption and cool-down time of Stirling engines by several tens of percent.
One of the major challenges of InAs/GaSb superlattice devices arises owing to the large number of surface states generated during fabrication processes. Surface passivation and subsequent capping of the surfaces are essential for any practical applicability of this material system. In this paper, we passivated InAs/GaSb superlattice infrared detectors proposed anodic fluoride passivation method. Short and mid wavelength InAs/GaSb superlattice infrared materials were grown by Molecular Beam Epitaxy (MBE) on GaSb (100) substrates. A GaSb buffer layer was grown for optimized superlattice growth condition, which can decrease the occurrence of defects with similar pyramidal structure. The result of auger electron spectroscopy (AES) surface scans after anodic fluoride passivation confirms that anodic fluoride passivation treatment did affect. The leakage current as a function of bias voltage (I-V) for InAs/GaSb superlattice infrared detectors has been examined at 77K. Compared with the unpassivated approach, this passivation methods decrease the dark current by approximately five orders of magnitude.
Indium tin oxide (ITO) films were deposited on sapphire substrates at temperatures ranging from 30°C to 700°C and oxygen background pressure changing from 0.05 Pa to 0.25 Pa by femtosecond pulsed laser deposition (PLD). The films were characterized using metallurgical microscope, film resistance meter and Fourier transform infrared spectrometer to study the effect of substrate temperature and oxygen background pressure on the surface topography, sheet resistance and infrared transmission. The photographs of metallurgical microscope show that substrate temperature plays a dominant role on the surface morphology of the films. The sheet resistance test suggests that the sheet resistance of the film decreases with increase of substrate temperature but increases with increase of oxygen background pressure. The results of infrared transmission show that the infrared transmission through the ITO film is about 40% at the wavelength of 1.5μm to 1.8μm and is very low at other infrared band. The films deposited at higher substrate temperatures show lower value of transmittance, and which at higher oxygen background pressure show higher value of transmittance.
A series of InSb thin films were fabricated on the sapphire substrate by femtosecond pulsed laser deposition (fsPLD)
method with the laser of 110 fs pulse width. The laser incident energy is near 1mJ. The target is one kind of heavily
doped n-type InSb. The substrate temperature changes from 80 ºC to 400 ºC, Laser frequency changes from 1 Hz to 1 kHz and laser energy density changes from 0.1 J/cm2 to 1 J/cm2. The effects of different laser frequencies, substrate temperature and laser energy density on the surface morphology and optical property have been investigated separately. The surface morphology of InSb thin films was observed by metallurgical microscope and scanning electron microscope (SEM). The thin film with better surface morphology is obtained when the laser frequency is 10 Hz, substrate temperature is 80 ºC and laser energy density is 0.1 J/cm2. X-ray diffraction (XRD) demonstrates that the InSb thin film has a good single crystal structure. The infrared transmittance of InSb thin films is measured by an infrared spectrometer. The results show that good InSb thin films can be prepared by fsPLD. It is found that the mid-wavelength Infrared transmission through the InSb thin films is near 55% and it almost does not change under the different growing conditions.
We have measured room temperature x-ray absorption spectroscopy (XAS) at the Mn L2,3edges on ferromagnetic Ga1-xMnxAs films prepared under different As2/Ga flux ratios. A growth
condition relative energy shift (ΔE) at L2 peak was observed, the results suggest that the formation
of antiferromagnetic Mn-As complex under As-rich growth conditions and the energy shift can be
weakened even eliminated by post-growth low temperature (LT) annealing. The intensity of XAS
spectrum was promoted after post-growth annealing, and the effect of annealing was also
influenced by growth conditions.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.