Arizona State University

Arizona Board of Regents, a Body Corporate

Tokyo Electron Limited

Yong-Hang Zhang

Shane R Johnson

Wolfgang Braun

Philip Dowd

Wayne L Johnson

Oray Orkun Cellek

Hanqing Jiang

Kevin O'Brien

Hongbin Yu

Zachary Holman

Elizabeth H Steenbergen

Ding Ding

Stephen T Schaefer

Yuan Zhao

Zhaoyu He

Chang-Zhi Guo

Zhi-Yuan Lin

Xin Qi

Zheng Ju

Jia Ding

Tyler Mccarthy

Jing-Jing Li

Swee Hoe Lim

Mathieu Boccard

Cunjiang Yu

Contacts for solar cells and other optoelectronic devices are provided. Embodiments described herein take advantage of the surface Fermi level pinning effect to build an electrical field inside of a semiconductor to extract or inject carriers for solar cells, photodetectors, and light-emitting device applications. For example, n-type or p-type two-dimensional (2D) materials can be used in contact with an n-type semiconductor to form a 'p-region' so that a p-n junction, or an i-n or n-n+ junction can be constructed. Similarly, n-type or p-type 2D materials can be used in contact with a p-type semiconductor to form an “n-region” so that an n-p junction, or an i-p or p-p+ junction can be constructed. These structures can provide sufficiently high electrical field inside the semiconductor to extract photogenerated carriers in solar cells and photodetectors or inject minority carriers for light-emitting devices.

Contacts of solar cells and other optoelectronic devices

Devices converting light to electricity (such as solar cells or photodetectors) including a heavily-doped p-type a-SiC:H and an i-MgCdTe/n-CdTe/N&#x2014;MgCdTe double heterostructure (DH), with power conversion efficiency of as high as 17%, Vas high as 1.096 V, and all operational characteristics being substantially better than those of monocrystalline solar cells known to-date. The a-SiC:H layer is configured to enable high built-in potential while, at the same time, allowing the doped absorber to maintain a very long carry lifetime. In comparison, similar undoped CdTe/MgCdTe DH designs reveal a long carrier lifetime of 3.6 &#x3bc;s and an interface recommendation velocity of 1.2 cm/s, which are lower than the record values reported for GaAs/AlGaAs (18 cm/s) and GaAs/GaInP (1.5 cm/s) DHs.

CdTe-based double heterostructures and related light-conversion devices

A CCD with an internal heterostructure well to store the photogenerated carriers is realized by using barrier and absorber semiconductors with a type-II band alignment in nBn or pBp photodetectors to form a specific barrier configured to confine the depletion region and a well to trap and store the photogenerated minority carriers. Depending on the spectral regime, (InAs/InAsSb)/(InAs/AlGaSb) superlattices can be used in the infrared, Si/Ge or AlP/GaP in the visible portion of optical spectrum, and GaN/ZnO in the UV portion. The resulting device not only leverages the advantages of the conventional CCD (such as in-pixel signal integration to suppress the noise), but also boasts an advantageously low operational voltage, thereby ensuring the low power consumption and low band-to-band tunneling current/noise (in particular, for use as an infrared photodetector). In comparison with IR FPAs of related art, the cost of the device is reduced and no flip-chip mount on a read-out integrated circuit is required during the fabrication process.

Low-voltage charge-coupled devices with a heterostructure charge-storage well

Systems and methods for a real-time baseline correction technique for infrared time-resolved photoluminescence are disclosed.

Real-time baseline correction technique for infrared time-resolved photoluminescence

A pulsed voltage bias method and/or pulsed light bias method may be used to reduce, minimize, and/or eliminate external quantum efficiency measurement artifacts of multi-junction solar cells, for example artifacts caused by the shunt effect. In this manner, multi-junction solar cells may be designed and constructed with improved performance, efficiency, and the like.

Systems and methods for eliminating measurement artifacts of external quantum efficiency of multi-junction solar cells

Multi-band photodetectors can be formed by series connecting unipolar and, optionally, bipolar semiconductor structures, each having different photodetection bands. Under default mode of operation, the detector with highest resistance and lowest current will be the current limiting device and will be the active photodetector. When the active photodetector is illuminated with strong light in its own detection band it will be optically biased. This active photodetector will no longer be the highest resistance device, and the next photodetector will be the active photodetector. Repeating this operation pattern, allows switching photodetection bands of the multi-band photodetector. The resistances, dark current and photocurrent of the devices should be engineered to have proper switching. Moreover, the illuminating surface, and photodetector placement should be optimized for proper light biasing. The current passing through the device will always be equal to the current of the active photodetector.

Multiband photodetector utilizing serially connected unipolar and bipolar devices

Use of semiconductor materials having a lattice constant of within +/&#x2212;1.6% of 6.1 angstroms facilitates improved semiconductor device performance and new semiconductor structures, for example integration of field-effect devices and optoelectronic devices on a single wafer. High-mobility channels are enabled, improving device performance.

6.1 angstrom III-V and II-VI semiconductor platform

Described herein are diffraction gratings and methods for the manufacture thereof. One method comprises applying a force to a substrate to strain the substrate, disposing a thin film on at least a portion of the substrate, and reducing the force applied to the substrate, thereby causing the thin film to buckle.

Optical diffraction gratings and methods for manufacturing same

Two-terminal multi junction photodetectors and focal plane arrays for multi-color detection or imaging acquisition can be formed by connecting photodiodes with different bandgaps or wavelengths, through tunnel diodes, in series with the same polarization. Under reverse bias in the dark, the total current going through such multi junction photodetectors is dictated by the smallest reverse saturation current of the photodiodes. When in operating mode, a set of light sources with different wavelengths corresponding to each individual photodiode can be used to optically bias all the photodiodes except the detecting photodiode Under illumination, all other photodiodes work in the photovoltaic mode and have much higher maximum possible reverse currents than the detecting photodiode. As a result, the total current of the multi junction photodetector is dictated by the detecting photodiode. Therefore, a total current can be read by, for example, read-out circuits to give the optical signal strength at that specific wavelength of the detecting photodiode. By using an algorithm one can use such multi junction photodetectors to detect different wavelengths and to take multicolor images.

Two-terminal multi-color photodetectors and focal plane arrays

An apparatus () using specular reflection spectroscopy to measure a temperature of a substrate (). By reflecting light () from a substrate, the temperature of the substrate can be determined using the band-edge characteristics of the substrate. This in situ apparatus can be used as a feedback control in combination with a variable temperature substrate holder to more accurately control the processing conditions of the substrate. By utilizing a multiplicity of measurement sites, the variation of the temperature across the substrate can also be measured.

Apparatus for measuring temperatures of a wafer using specular reflection spectroscopy

The invention discloses improved structures of light-processing (e.g. light-emitting and light-absorbing/sensing) devices, in particular Vertical Cavity Surface Emitting Lasers (VCSELs), such as may find use in telecommunications applications. The disclosed VSCAL devices and production methods provide for an active region having a quantum well structure grown on GaAs-containing substrates, thus providing processing compatibility for light having wavelength in the range 1.0 to 1.6 &#x3bc;m. The active region structure combines strain-compensating barriers with different band alignments in the quantum wells to achieve a long emission wavelength while at the same time decreasing the strain in the structure. The improved functioning of the devices disclosed results from building them with multicomponent alloy layers having a large number of constituents. The invention discloses as a key constituent in the proposed alloy layers for the active region a substance, such as nitrogen (N), suitable for reducing bandgap energy (i.e., increasing light wavelength) associated with the layers while at the same time lowering the lattice constant associated with the structure and hence lowering strain.

Long wavelength pseudomorphic InGaNPAsSb type-I and type-II active layers for the gaas material system

A compound semiconductor device is provided that includes a substrate and an active region disposed above the substrate. The active region includes at least two different pseudomorphic layers, the first layer having the form In Ga P As Sb , and the second layer having the form In Ga P As Sb . The first layer includes at least In, Ga, and As, and the second layer includes at least Ga, As, and Sb. It is preferable for the substrate to be GaAs or Al Ga As (0<p<1), or to have a lattice constant close to or equal to that of GaA For the first layer, it is preferable if x is between 0.05 and 0.7, y is between 0 and 0,35, z is between 0.45 and 1, and 1&minus;y&minus;z is between 0 and 0.25. For the second layer, it is preferable if q is between 0 and 0.25 and 1&minus;r&minus;s is between 0.25 and 1.

Growing community of inventors

Scottsdale, AZ, United States of America

Yong-Hang Zhang