Publications by    
Page 1 of 2:  1  2  >> Next  (42 Items)

1.  Advanced Monolithic Quantum Well Infrared Photodetector Focal Plane Array Integrated with Silicon Readout Integrated Circuit
J. Jiang, S. Tsao, K. Mi, M. Razeghi, G.J. Brown, C. Jelen and M.Z. Tidrow
Infrared Physics and Technology, 46 (3)-- January 1, 2005
Today, most infrared focal plane arrays (FPAs) utilize a hybrid scheme. To achieve higher device reliability and lower cost, monolithic FPAs with Si based readout integrated circuits (ROICs) are the trend of the future development. In this paper, two approaches for monolithic FPAs are proposed: double sided integration and selective epitaxy integration. For comparison, the fabrication process for hybrid quantum well infrared photodetectors (QWIP) FPAs are also described. Many problems, such as the growth of QWIPs on Si substrate and processing incompatibility between Si and III–V semiconductors, need to be solved before monolithic FPAs can be realized. Experimental work on GaInAs/InP QWIP-on-Si is given in this paper. A record high detectivity of 2.3×109 jones was obtained for one QWIP-on-Si detector at 77 K. reprint
2.  Demonstration of 256x256 Focal Plane Arrays Based on Al-free GaInAs/InP QWIP
J. Jiang, K. Mi, R. McClintock, M. Razeghi, G.J. Brown, and C. Jelen
IEEE Photonics Technology Letters 15 (9)-- September 1, 2003
We report the first demonstration of an infrared focal plane array based on aluminum-free GaInAs-InP quantum-well infrared photodetectors (QWIPs).A unique positive lithography method was developed to perform indium-bump liftoff. The noise equivalent differential temperature (NEΔT) of 29 mK was achieved at 70 K with f/2 optics. reprint
3.  High Detectivity GaInAs/InP Quantum Well Infrared Photodetectors Grown on Si Substrates
J. Jiang, C. Jelen, M. Razeghi and G.J. Brown
IEEE Photonics Technology Letters 14 (3)-- March 1, 2002
In this letter, we report an improvement in the growth and the device performance of GaInAs-InP quantum well infrared photodetectors grown on Si substrates. Material growth techniques, like low-temperature nucleation layers and thick buffer layers were used to grow InP on Si. An in situ thermal cycle annealing technique was used to reduce the threading dislocation density in the InP-on-Si. Detector dark current was reduced 2 orders of magnitude by this method. Record high detectivity of 2.3 × 109 cm·Hz½·W-1 was obtained for QWIP-on-Si detectors in the 7-9 μm range at 77 K reprint
4.  Quantum Dot Intersubband Photodetectors
C. Jelen, M. Erdtmann, S. Kim, and M. Razeghi
SPIE Conference, San Jose, CA, -- January 22, 2001
Quantum dots are recognized as very promising candidates for the fabrication of intersubband photodetectors in the infrared spectral range. At present, material quality is making rapid progress and some devices have been demonstrated. Examples of mid-infrared quantum dot intersubband photodetectors are presented along with device design and data analysis. Nonetheless, the performance of these devices remains less than comparable quantum well intersubband photodetectors due to difficulties in controlling the quantum dot size and distribution during epitaxy. reprint
5.  AlxGa1-xN Materials and Device Technology for Solar Blind Ultraviolet Photodetector Applications
R. McClintock, P. Sandvik, K. Mi, F. Shahedipour, A. Yasan, C. Jelen, P. Kung, and M. Razeghi
SPIE Conference, San Jose, CA, Vol. 4288, pp. 219-- January 22, 2001
There has been a growing interest for the development of solar blind ultraviolet (UV) photodetectors for use in a variety of applications, including early missile threat warning, flame monitoring, UV radiation monitoring and chemical/biological reagent detection. The AlxGa1-xN material system has emerged as the most promising approach for such devices. However, the control of the material quality and the device technology are still rather immature. We report here the metalorganic chemical vapor deposition, the n-type and the p-type doping of high quality AlxGa1-xN thin films on sapphire substrates over a wide range of Al concentration. reprint
6.  Long-Wavelength Quantum Well Infrared Photodetectors
M. Razeghi, M. Erdtmann, C. Jelen, J. Diaz, F. Guastavino and Y.S. Park
-- January 1, 2001
7.  Development of Quantum Well Infrared Photodetectors at the Center for Quantum Devices
M. Razeghi, M. Erdtmann, C. Jelen, J. Diaz, F. Guastavino, G.J. Brown, and Y.S. Park
-- January 1, 2001
8.  Low-threshold and high power (~9.0 μm) quantum cascade lasers operating at room temperature
A. Matlis, S. Slivken, A. Tahraoui, K.J. Luo, J. Diaz, Z. Wu, A. Rybaltowski, C. Jelen, and M. Razeghi
Applied Physics Letters 77 (12)-- September 18, 2000
We report a low threshold current density and high power for λ ∼ 9 μm AlInAs/GaInAs quantum cascade lasers operating at room temperature. The threshold current density is 1.95 kA/cm² at 300 K and 0.61 kA/cm² at 80 K for 5 μs pulses at 200 Hz repetition rate. The peak output power is 700 mW at room temperature and 1.3 W at 80 K per two facets for cavity length is 3 mm with a stripe width of 20 μm. The characteristic temperature T0 is 185 °C. The slope efficiency is 450 and 800 mW/A at 300 and 80 K, respectively. In continuous wave operation, the output power is more than 150 mW at 80 K and 25 mW at 140 K. This high performance was achieved by improving the material growth and processing technology. reprint
9.  Quantum Well Infrared Photodetectors (3 - 20 μm) Focal Plane Arrays: Monolithic Integration with Si-based Readout-integrated Circuitry for Low Cost and High Performance
M. Razeghi, M. Erdtmann, C. Jelen, J. Diaz, F. Guastavino, G. J. Brown, and Y.S. Park
-- July 30, 2000
10.  High-responsivity GaInAs/InP Quantum Well Infrared Photodetectors Grown by Low-Pressure Metalorganic Chemical Vapor Deposition
M. Erdtmann, A. Matlis, C. Jelen, M. Razeghi, and G. Brown
SPIE Conference, San Jose, CA, -- January 26, 2000
We have studied the dependence of the well doping density in n-type GaInAs/InP quantum well IR photodetectors (QWIPs) grown by low-pressure metalorganic chemical vapor deposition. Three identical GaInAs/InP QWIP structures were grown with well sheet carrier densities of 1x1011 cm-2, 3x1011 cm-2, and 10x1011 cm-2; all three samples had very sharp spectral response at λ equals 9.0 μm. We find that there is a large sensitivity of responsivity, dark current, noise current, and detectivity with the well doping density. Measurements revealed that the lowest-doped samples had an extremely low responsivity relative to the doping concentration while the highest-doped sample had an excessively high dark current relative to doping. The middle-doped sample yielded the optimal results. This QWIP had a responsivity of 33.2 A/W and operated with a detectivity of 3.5x1010 cm·Hz½·W-1 at a bias of 0.75 V and temperature of 80 K. This responsivity is the highest value reported for any QWIP in the (lambda) equals 8-9 &mus;m range. Analysis is also presented explaining the dependence of the measured QWIP parameters to well doping density. reprint
11.  Growth and Optimization of GaInAsP/InP Material System for Quantum Well Infrared Photodetector Applications
M. Erdtmann, J. Jiang, A. Matlis, A. Tahraoui, C. Jelen, M. Razeghi, and G. Brown
SPIE Conference, San Jose, CA, -- January 26, 2000
Multi-quantum well structures of GaxIn1-xAsyP1-y were grown by metalorganic chemical vapor deposition for the fabrication of quantum well IR photodetectors. The thickness and composition of the wells was determined by high-resolution x-ray diffraction and photoluminescence experiments. The intersubband absorption spectrum of the Ga0.47In0.53As/InP, Ga0.38In0.62As0.80P0.20 (1.55 μm)/InP, and Ga0.27In0.73As0.57P0.43 (1.3 μm))/InP quantum wells are found to have cutoff wavelengths of 9.3 μm, 10.7 micrometers , and 14.2 μm respectively. These wavelengths are consistent with a conduction band offset to bandgap ratio of approximately 0.32. Facet coupled illumination responsivity and detectivity are reported for each composition. reprint
12.  Solar-Blind AlxGa1-xN p-i-n Photodetectors grown on LEO and non-LEO GaN
P. Sandvik, D. Walker, P. Kung, K. Mi, F. Shahedipour, V. Kumar, X. Zhang, J. Diaz, C. Jelen, and M. Razeghi
SPIE Conference, San Jose, CA, Vol. 3948, pp. 265 -- January 26, 2000
The III-Nitride material system is an excellent candidate for UV photodetector applications due to its wide, direct bandgaps and robust material nature. However, despite many inherent material advantages, the III-Nitride material system typically suffers from a large number of extended defects which degrade material quality and device performance. One technique aimed at reducing defect densities in these materials is lateral epitaxial overgrowth (LEO). In this work, we present a preliminary comparison between AlGaN UV, solar-blind p-i-n photodiodes fabricated form LEO GaN and non-LEO GaN. Improvements in both responsivity and rejection ratio are observed, however, further device improvements are necessary. For these, we focus on the optimization of the p- i-n structure and a reduction in contact resistivity to p- GaN and p-AlGaN layers. By improving the structure of the device, GaN p-i-n photodiodes were fabricated and demonstrate 86 percent internal quantum efficiency at 362 nm and a peak to visible rejection ratio of 105. Contact treatments have reduced the contact resistivity to p-GaN and p-AlGaN by over one order of magnitude form our previous results. reprint
13.  AlGaInAs/InP-based Quantum Well Infrared Photodetectors
C. Jelen and M. Razeghi
-- March 1, 1999
14.  Multi-color 4–20 μm In-P-based Quantum Well Infrared Photodetectors
C. Jelen, S. Slivken, G.J. Brown, and M. Razeghi
SPIE Conference, San Jose, CA, -- January 27, 1999
In order to tune the wavelength of lattice-matched QWIP detectors over the range from 4 - 20 &mum, new designs are demonstrated for the first time which combine InGaAlAs and InGaAsP layers lattice-matched to InP and grown by gas-source molecular beam epitaxy. We demonstrate the first long-wavelength quantum well infrared photodetectors using the lattice-matched n-doped InGaAlAs/InP materials system. Samples with AlAs mole fractions of 0.0, 0.1, and 0.15 result in cutoff wavelengths of 8.5, 13.3, and 19.4 μm, respectively. A 45 degree facet coupled illumination responsivity of R equals 0.37 A/W and detectivity of D*(λ) equals 1x109 cm·Hz½·W-1 at T = 77 K, for a cutoff wavelength λc equals 13.3 μm have been achieved. Based on the measured intersubband photoresponse wavelength, a null conduction band offset is expected for In0.52Ga0.21Al0.27As/InP heterojunctions. We also report quantum well infrared photodetector structures of In0.53Ga0.47As/Al0.48In0.52As grown on InP substrate with photoresponse at 4 μm suitable for mid-wavelength infrared detectors. These detectors exhibit a constant peak responsivity of 30 mA/W independent of temperature in the range from T equals 77 K to T equals 200 K. Combining these two materials, we report the first multispectral detectors that combine lattice-matched quantum wells of InGaAs/InAlAs and InGaAs/InP. Utilizing two contacts, a voltage tunable detector with (lambda) p equals 8 micrometer at a bias of V equals 5 V and λp equals 4 μm at V equals 10 V is demonstrated. reprint
15.  High Temperature Continuous Wave Operation of ~8 μm Quantum Cascade Lasers
S. Slivken, A. Matlis, C. Jelen, A. Rybaltowski, J. Diaz, and M. Razeghi
Applied Physics Letters 74 (2)-- January 11, 1999
We report single-mode continuous-wave operation of a λ∼8 μm quantum cascade laser at 140 K. The threshold current density is 4.2 kA/cm² at 300 K in pulsed mode and 2.5 kA/cm² at 140 K in continuous wave for 2 mm long index-guided laser cavities of 20 μm width. Wide stripe (W ∼ 100 μm), index-guided lasers from the same wafer in pulsed operation demonstrate an average T0 of 210 K with other wafers demonstrating a T0 as high as 290 K for temperatures from 80 to 300 K. This improvement in high-temperature performance is a direct result of three factors: excellent material quality, a low-loss waveguide design, and a low-leakage index-guided laser geometry. reprint
16.  Low Threshold Quantum Cascade Lasers Grown by GSMBE
M. Razeghi, S. Slivken, A. Matlis, A. Rybaltowski, C. Jelen, and J. Diaz
-- December 1, 1998
17.  InGaAlAs/InP Quantum Well Infrared Photodetectors for 8-20 μm Wavelengths
C. Jelen, S. Slivken, V. Guzman, M. Razeghi, and G. Brown
-- October 1, 1998
18.  Growth and characterization of InGaAs/InGaP quantum dots for mid-infrared photoconductive detector
S. Kim, H. Mohseni, M. Erdtmann, E. Michel, C. Jelen and M. Razeghi
Applied Physics Letters 73 (7)-- August 17, 1998
We report InGaAs quantum dot intersubband infrared photodetectors grown by low-pressure metalorganic chemical vapor deposition on semi-insulating GaAs substrates. The optimum growth conditions were studied to obtain uniform InGaAs quantum dots constructed in an InGaP matrix. Normal incidence photoconductivity was observed at a peak wavelength of 5.5 μm with a high responsivity of 130 mA/W and a detectivity of 4.74×107  cm· Hz½/W at 77 K. reprint
19.  Noise performance of InGaAs/InP quantum well infrared photodetectors
C. Jelen, S. Slivken, T. David, M. Razeghi and G. J. Brown
-- July 7, 1998
20.  Responsivity and Noise Performance of InGaAs/InP Quantum Well Infrared Photodetectors
C. Jelen, S. Slivken, T. David, G. Brown, and M. Razeghi
SPIE Conference, San Jose, CA, -- January 28, 1998
Dark current nose measurements were carried out between 10 and 104 Hz at T = 80K on two InGaAs/InP quantum well IR photo detectors (QWIPs) designed for 8 μm IR detection. Using the measured noise data, we have calculated the thermal generation rate, bias-dependent gain, electron trapping probability, and electron diffusion length. The calculated thermal generation rate is similar to AlGaAs/GaAs QWIPs with similar peak wavelengths, but the gain is 50X larger, indicating improved transport and carrier lifetime are obtained in the binary InP barriers. As a result, a large responsivity of 7.5 A/W at 5V bias and detectivity of 5 X 1011 cm·Hz½/W at 1.2 V bias were measured for the InGaAs/InP QWIPs at T = 80K. reprint
21.  InP-based Multi-Spectral Quantum Well Infrared Photodetectors
C. Jelen and M. Razeghi
-- December 11, 1997
22.  Gas-Source Molecular Beam Epitaxy Growth of 8.5 μm Quantum Cascade Laser
S. Slivken, C. Jelen, A. Rybaltowski, J. Diaz and M. Razeghi
Applied Physics Letters 71 (18)-- November 1, 1997
We demonstrate preliminary results for an 8.5 μm laser emission from quantum cascade lasers grown in a single step by gas-source molecular beam epitaxy. 70 mW peak power per two facets is recorded for all devices tested at 79 K with 1 μs pulses at 200 Hz. For a 3 mm cavity length, lasing persists up to 270 K with a T0 of 180 K. reprint
23.  High-Quality Quantum Cascade Lasers Grown by GSMBE
S. Slivken, C. Jelen, J. Diaz, and M. Razeghi
-- October 1, 1997
24.  Photoresponse of InGaAsP-based p-doped quantum well infrared photodetectors
M. Tadic, C. Jelen, S. Slivken, and M. Razeghi
-- September 14, 1997
25.  In-plane electron dynamics and hot electron effects in a quantum cascade laser
M. Tadic, C. Jelen, S. Slivken, and M. Razeghi
-- September 14, 1997

Page 1 of 2:  1  2  >> Next  (42 Items)