In this work, an innovated Si3N4 as an out-diffusion barrier layer to Au/Zn/Au contact system for p-type InP has been
proposed. Before the contacts were annealed, Si3N4 layer was deposited on the Au(200Å)/Zn(700Å)/Au(200Å), then the
Si3N4 was removed by HF and a 2000A layer of pure gold was deposited to facilitate wire bonding. The specific contact
resistance dropped to a minimum value of 6×10-7 Ω • cm2 (for an acceptor concentration of about 3×1018cm-3) and the
contact became perfectly Ohmic. Besides, Si3N4 layer is an excellent passivation layer and antireflection coating in
InP/InGaAs/InP (p-i-n) photodiodes.
The uncooled InGaAs-based infrared detector has received great interest in recent years for its application in optical-fiber
communication and remote sensing. However, the improvement of device performance is hampered by the lack of
feasible method to monitor its device process. The Microwave Photoconductivity Decay (μ-PCD) technique is a
contactless and non-destructive technique of the recombination lifetime characterization and mapping and has found
wide application in semiconductor research. In this paper, a double heterojunction p-i-n InP/In0.53Ga0.47As/InP mesa
structure was fabricated by Ar+ ion etching and the μ-PCD technique was applied to characterize the electrical effects of
ion etching on this structure. The results revealed that the built-in field in the p-n junction played a critical role in
recombination of photo induced minority carriers which made the mesa structure identifiable but not identical with the
lifetime mapping of the sample. The recombination lifetime in the mesa was dominated by the recombination process in
the edge of the mesa. The lifetime in the etched region was also influenced by the built-in field and increased with the
decrease of distance to the mesa area. And ion etching brought great nonuniformity to the photo active cells.
In this paper, 256 elements front-illuminated InGaAs mesa detector arrays were fabricated based on doped-InGaAs
absorbing layer in MOCVD-grown p-InP/n-InGaAs/n-InP
double-heterostructure epitaxial materials. The processing
includes mesa-making, SiNx passivation, growth of electrodes and so on. The current-voltage, capacitance-voltage
characteristics and response spectrum of the detector were measured. The results indicate that the InGaAs detector has
typical dark current about 0.9 nA at 0.5 V reverse-bias voltage, a capacitance as low as 49 pF at 1 reverse-bias voltage,
and the peak wavelength and cutoff wavelength at 1.57μm and 1.68μm respectively. The InGaAs detector arrays were
connected with two CTIA-structured L128 read-out integrated circuits, and the response signal and noise were obtained.
At room temperature, the mean peak detectivity of the InGaAs focal plane arrays (FPAs) is 1.9×1012
cmHz1/2W-1, and the
non-uniformity of response is superior to 6%. The laser beam induced current (LBIC) technique was used to investigate
the crosstalk and photoactive area of the InGaAs detectors. Its results indicate that there is little crosstalk between two
neighbor InGaAs detectors, about 7%. The photoactive area of InGaAs detector extends about 4.5 μm, and the reason is analyed in the paper.
In this work, the performance of InxGa1-xAs photovoltaic detectors with cutoff wavelength of 2.4μm(x=0.78) were
investigated. The detector arrays were fabricated using gas source molecular beam epitaxy (GSMBE) grown material and
arranged in linear arrays of 256 pixels of 56×56μm2 dimension. The transition of the large lattice mismatch (1.6%)
between the substrate and the absorption layer was dealt with a linearity transformation InxGa1-xAs buffer layer. The
dark-current performance achieved is as low as 10-10A at 300K and a bias voltage of -0.5V. This corresponds to a figure
of merit for detector resistance R0 times detector pixel area A of R0A =3.5~7.5Ωcm2 at 300K and quantum efficiency
above 60%. Room temperature D*(λp) values beyond 3×1010cmHz1/2W-1.
We found that the contact resistance of Au/Pt/Ti on p-InP increases with the increase of annealing time and annealing
temperature. Au/Pt/Ti is ohmic contact metal as deposited with specific contact resistance of 2.49×10-3 Ωcm2 when p-InP
doped by 7.5×1018 cm-3 and is Schottky contact when doped by 2×1018 cm-3. Surface morphologies of Au/Pt/Ti after rapid
thermal processing (RTP) were analyzed by atom force microscopy (AFM). An interface layer dominated by TiIn
compound, which increase the specific contact resistance, was found in Auger electron spectroscopy (AES) analysis.
P-InP and n-InP ohmic contacts can be achieved at the same time as deposited when added p-In0.53Ga0.47As layer on
p-InP/InGaAs/n-InP without annealing.