A high temperature operation mid-wavelength 128×128 infrared focal plane arrays (FPA) based on low Al component In<sub>1-x</sub>Al<sub>x</sub>Sb 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.
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.
InAs/GaSb superlattice material was grown on GaAs substrates by Molecular-beam epitaxy(MBE). To study the Ohmic
contact and electrical property of InAs/GaSb superlattices, the Au//Ti/InAs/GaSb superlattices contact was fabricated
using heated electron evaporation methods on the surface of InAs/GaSb superlattices. The Au//Ti/InAs/GaSb
superlattices contact character was analyzed by transmission line model. The results show that Au//Ti/InAs/GaSb
superlattices contact is the Ohmic contact with good contact resistivity. And it meets requirement of Ohmic contact with
the perfect quality. The electrical properties of InAs/GaSb superlattices were tested by Van Der Pauw. That means the
leak current decrease as the carriers density reaches to a lower level. At the meantime, the detector obtains a better
background noise and energy resolution.
Inductively coupled plasma (ICP) etching of GaSb and InAs/GaSb super lattices were performed using Cl<sub>2</sub>/Ar plasma. The effects of GaSb of etching time, Cl<sub>2</sub>: Ar ratio and RF power on etching rates were investigated. It is found that the etching rates were relatively low when etch time was less than 2 min, After etching for 3 min, the etching rates was about 1.3 μm/min as a result of constant, also, the etching rate was increased monotonically with the increasing of Cl<sub>2</sub> proportion, and reaches at 4.14 μm/min when the Cl<sub>2</sub> concentration is 80%. In contrast, the peak value of etching rate of InAs/GaSb super lattices is 1.37 μm/min and the increase extent of etching rates of InAs/GaSb super lattices was much lower than that of GaSb, mainly owing to the insensitivity of InAs to the Cl<sub>2</sub> concentration. In addition, the etching rates of GaSb increased slowly with the increasing of RF power, which indicated the less efficiency influence of RF power on etching rate. The surface morphology of etched InAs/GaSb super lattices was characterized by WYKO HD3300 head measurement system, which suggested that the surface morphology was becoming rough with the increase of Cl<sub>2</sub> percentage. When the concentration reaches 60%, the surface morphology was unacceptable. The results showed that contrast to wet chemical etching, dry etching can form smoother pattern, which indicates the promising application in fabricating fine devices.
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/cm<sup>2</sup> to 1 J/cm<sup>2</sup>. 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/cm<sup>2</sup>. 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.
Accurate and reliable numerical simulation tools are necessary for the development of advanced semiconductor devices. InSb is using the MATLAB and TCAD simulation tool to calculatet the InSb body bandstructure, blackbody's radiant emittance and simultaneously solve the Poisson, Continuity and transport equations for 2D detector structures. In this work the material complexities of InSb, such as non-parabolicity, degenergcy, mobility and Auger recombination/generation are explained, and physics based models are developed. The Empirical Tight Binding Method (ETBM) was been using to calculate the bandstructure for InSb at 77 K by Matlab. We describe a set of systematic experiments performed in order to calibrate the simulation to semiconductor devices backside illuminated InSb focal plane arrays realized with planar technology. The spectral photoresponse and crosstalk characteristic for mid-wavelength InSb infrared focal plane arrays have been numerically studied.
We present the high performance of Hg<sub>3</sub>In<sub>2</sub>Te6 metal-semiconductor photodetectors using Indium tin oxide (ITO) as the
schottky electrodes by vacuum magnetron sputtering.There is a interfacial oxide layer formation by oxygen plasma
process between Indium tin oxide (ITO) and Hg<sub>3</sub>In<sub>2</sub>Te<sub>6</sub> semiconductor compound to change schottky barrier. The effects
of oxygen plasma treatment on Hg<sub>3</sub>In<sub>2</sub>Te<sub>6</sub> surface property were studied. Under optimized condition, the surface of
Hg<sub>3</sub>In<sub>2</sub>Te<sub>6</sub> is oxidated resulting in decreasing reverse dark current and increasing breakdown voltage, while the barrier
height increases from 0.5 to 0.58eV. This method is simple to fabricate high performance HgInTe devices.
Photodiodes designed to be sensitive in the region 1.4~1.7μm and obtained by vacuum magnetron
sputtering of the Pt layer on the surface of the HgInTe single crystal are studied. Temperature dependence
on electrical characteristics of the crystal and the Schottky diodes were investigated in a temperature range
from 120K to260K. The current-voltage characteristics of the diodes show excellent rectification behavior.
Temperature dependence on the ideality factor and apparent barrier height was determined, including the
effect of series resistance. The evaluated ideality factor was observed to decrease from 2.93 to 1.42, while
the apparent barrier height is 0.563 in this temperature range. The temperature dependence of the forward
characteristics can be well explained by thermionic emission theory. The measured barrier height for Pt on
HgInTe is similar to the value reported for both ITO and Au rectifying contacts on this material. A possible
mechanism of the correlation of the ideality factor and barrier height has been proposed.
Attempt to form the Schottky barrier on mercury indium telluride (MIT) surface by deposition transparent conducting
electrode (TCE) and avoid the negative results by non-rectifier contacts nature, we have investigated the oxidation of
clean MIT surfaces to form an insulating layer to overcome this disadvantage by metal-insulator-semiconductor (MIS)
photodetectors designing. Oxide film is grown on the MIT surface by plasma enhance chemical vapor deposition
(PECVD). Previously cleaned MIT wafers were dipped and boiled in solution, which consists of mixture of bromine and
an organic solvent in ratio of 1:50. By the way of using these films as intermediate slightly conducting insulator, a
fast-response MIT based surface-barrier photodetectors have been developed. Pt films were used as TCE frontal
electrode by vacuum magnetron sputtering (VMS). The current-voltage characteristic is described quantitatively based
on the energy diagram and the found parameters of the Schottky barrier. Details of oxidation process, Schottky diodes, as
well as the photodetectors fabrication and characterizations are discussed.