Near Infrared Response of Amorphous Silicon Detector Grown with Microcompensated Absorber Layer

1999 ◽  
Vol 557 ◽  
Author(s):  
D. Caputo ◽  
G. De Cesare ◽  
A. Nascetti ◽  
F. Palma ◽  
M. Tucci
Keyword(s):  
Amorphous Silicon ◽  
Communication Systems ◽  
Near Infrared ◽  
Silicon Detector ◽  
Optical Excitation ◽  
Absorber Layer ◽  
Trap States ◽  
Low Concentrations ◽  
Dopant Atoms ◽  
Device Operation

AbstractIn this work we demonstrate that radiation up to 2 μm induces photocurrent in a single junction amorphous silicon structure at room temperature. The absorber layer is a microcompensated film deposited using very low concentrations of dopant species. Device operation is based on optical excitation of thermal generated carriers from trap states toward valence and conduction band in the high electric field region of the structure. Transient and frequency response under different bias voltages and illuminations conditions are presented. The possibility to use the infrared sensor in low bit rate communication systems has been demostrated by including our detector in a front-end system and measuring its frequency responce.Quantum efficiency measurement have been reproduced with a numerical model, able to take into account sub-band gap absorption into single films. Model results indicate the presence of a large valence band tail and a high number of dangling bonds and shallow defects ascribed to the presence of dopant atoms.

Enhancing Light-trapping and Efficiency of Solar Cells with Photonic Crystals

2007 ◽  
Vol 989 ◽  
Author(s):  
Rana Biswas ◽  
Dayu Zhou
Keyword(s):  
Solar Cells ◽  
Photonic Crystal ◽  
Photonic Crystals ◽  
Amorphous Silicon ◽  
Near Infrared ◽  
Light Trapping ◽  
Absorber Layer ◽  
Diffract Light ◽  
Major Route ◽  
Optical Wavelengths

AbstractA major route to improving solar cell efficiencies is by improving light trapping in solar absorber layers. Traditional light trapping schemes involve a textured metallic back reflector that also introduces losses at optical wavelengths. Here we develop alternative light trapping schemes with a-Si:H thin film solar cells, that do not use metallic components, thereby avoiding losses. We utilize low loss one-dimensional photonic crystals as distributed Bragg reflectors (DBR) at the backside of the solar cells. The DBR is constructed with alternating layers of crystalline Si and SiO2. Between the DBR and the absorber layer, there is a layer of 2D photonic crystal composed of amorphous silicon and SiO2. The 2D photonic crystal layer will diffract light at oblique angles, so that total internal reflection is formed inside the absorber layer. We have achieved enhanced light-trapping in both crystalline and amorphous silicon solar cells at near-infrared wavelengths where absorption lengths are very large. Very high absorption is achieved throughout optical wavelengths. The optical modeling is performed with a rigorous 3 dimensional scattering matrix approach where Maxwell¡¯s equations are solved in Fourier space.

A Novel Room Temperature Infrared Detector Using Micro-Compensated Amorphous Silicon

1998 ◽  
Vol 507 ◽  
Author(s):  
D. Caputo ◽  
G. De Cesare ◽  
A. Nascetti ◽  
F. Palma
Keyword(s):  
Amorphous Silicon ◽  
Infrared Radiation ◽  
Room Temperature ◽  
Infrared Detector ◽  
Differential Capacitance ◽  
Absorber Layer ◽  
Structure Capacitance ◽  
Extended States ◽  
Compensation Device ◽  
Device Operation

ABSTRACTDetection at room temperature of near and medium infrared radiation has been achieved by using micro-doped or micro-compensated amorphous silicon films as intermediate absorber layer in a p-n junction. Extremely low dopant concentrations in the gas mixture have been utilized to achieve micro-doping and micro-compensation. Device operation is based on transitions, induced by the infrared radiation, between extended states in the valence band and defects in the forbidden gap. The absorption process changes electron defect occupancy, giving rise to change in electric field distribution. This effect can be observed as variation of differential capacitance of the structure. Capacitance measurements, performed on two different devices with micro-doped and micro-compensated absorber layer respectively, showed sensitivity to radiation from 900 nm up to 4·5 jim.

scholarly journals Creation of Negatively Charged Boron Vacancies in Hexagonal Boron Nitride Crystal by Electron Irradiation and Mechanism of Inhomogeneous Broadening of Boron Vacancy-Related Spin Resonance Lines

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1373
Author(s):  
Fadis F. Murzakhanov ◽  
Boris V. Yavkin ◽  
Georgiy V. Mamin ◽  
Sergei B. Orlinskii ◽  
Ivan E. Mumdzhi ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Electron Irradiation ◽  
Near Infrared ◽  
Hexagonal Boron Nitride ◽  
Optical Excitation ◽  
High Energy ◽  
Infrared Range ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Spin Resonance

Optically addressable high-spin states (S ≥ 1) of defects in semiconductors are the basis for the development of solid-state quantum technologies. Recently, one such defect has been found in hexagonal boron nitride (hBN) and identified as a negatively charged boron vacancy (VB−). To explore and utilize the properties of this defect, one needs to design a robust way for its creation in an hBN crystal. We investigate the possibility of creating VB− centers in an hBN single crystal by means of irradiation with a high-energy (E = 2 MeV) electron flux. Optical excitation of the irradiated sample induces fluorescence in the near-infrared range together with the electron spin resonance (ESR) spectrum of the triplet centers with a zero-field splitting value of D = 3.6 GHz, manifesting an optically induced population inversion of the ground state spin sublevels. These observations are the signatures of the VB− centers and demonstrate that electron irradiation can be reliably used to create these centers in hBN. Exploration of the VB− spin resonance line shape allowed us to establish the source of the line broadening, which occurs due to the slight deviation in orientation of the two-dimensional B-N atomic plains being exactly parallel relative to each other. The results of the analysis of the broadening mechanism can be used for the crystalline quality control of the 2D materials, using the VB− spin embedded in the hBN as a probe.

Comparison of the Effect of Boron and Phosphorus Impurities on Solid Phase Epitaxial Regrowth of Amorphous Silicon

1989 ◽  
Vol 157 ◽  
Author(s):  
Young-Jin Jeon ◽  
M.F. Becker ◽  
R.M. Walser
Keyword(s):  
Amorphous Silicon ◽  
Isothermal Annealing ◽  
Solid Phase ◽  
Laser Interferometry ◽  
Electron Pairs ◽  
Quadratic Equations ◽  
Low Concentrations ◽  
Fractional Ionization ◽  
Reported Data

ABSTRACTThis work was concerned with comparing the relative effects of boron and phosphorus impurities on the solid phase epitaxial (SPE) regrowth rate of self-ion amorphized layers in silicon wafers with (100) orientation. We used previously reported data measured by in situ, high precision, cw laser interferometry during isothermal annealing for temperatures from 450°C to 590°C, and concentrations in the range from 7.8×1018 cm-3 to 5×l020 cm-3 for boron (NB), and from 5×l017 cm-3 to 3×1020 cm-3 for phosphorus (Np) impurities. The basis for the comparison was a recently developed model that extends the Spaepen-Turnbull model for silicon recrystallization to include ionization enhanced processes.The experimental data for bom boron and phosphorus exhibited the linear variation in regrowth rate expected for low concentrations of implanted hydrogenic impurities having a concentration-independent fractional ionization in amorphous silicon. In the linear range the relative enhanced regrowth rate produced by these impurities can be expressed as a product of their, relative fractional ionizations, and the relative amount the rate constant for reconstruction is altered by localizing an electron, or a hole, at the reconstruction site. Assuming that a localized hole and electron equally softened the potential barrier for reconstruction, the experimental results indicated that boron had an ?40 meV lower barrier to ionization in amorphous silicon than phosphorus.The variations in the SPE regrowth rates with higher concentrations of both implanted boron and phosphorus were well fit by quadratic equations, but with different curvatures (+ and - for B and P respectively). This result was interpreted to indicate that SPE regrowth was further enhanced by localized hole pairs, but retarded by localized electron pairs.

Near-infrared femtosecond laser-induced crystallization of amorphous silicon

2004 ◽  
Vol 85 (7) ◽  
pp. 1232-1234 ◽  
Author(s):  
Jia-Min Shieh ◽  
Zun-Hao Chen ◽  
Bau-Tong Dai ◽  
Yi-Chao Wang ◽  
Alexei Zaitsev ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Amorphous Silicon ◽  
Near Infrared ◽  
Induced Crystallization

Derelaxation of Amorphous Silicon by Ion Implantation: Optical Characterization

1991 ◽  
Vol 235 ◽  
Author(s):  
R. Reitano ◽  
M. G. Grimaldi ◽  
P. Baeri ◽  
E. Bellandi ◽  
A. Borghesi ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Short Range ◽  
Short Range Order ◽  
Structural Changes ◽  
Low Dose ◽  
Near Infrared ◽  
Ion Irradiation ◽  
Infrared Region ◽  
Range Order ◽  
Density Of State

ABSTRACTThe transition between relaxed and unrelaxed amorphous silicon can be obtained by thermal treatment of the unrelaxed amorphous or by low dose ion irradiation of the relaxed material. In both cases a variation in the short range order has been invoked to explain the behavior of the structural changes probed by various techniques. In this work we study the influence of such changes on the optical properties of a-Si in the region of the transition between the relaxed and the unrelaxed states. We show that a progressive variation of the optical constant in the visible-near infrared region upon derelaxation occurs. Therefore, significant modifications of the electron density of state in the region above the optical gap are associated with the changes in the short range order probed by Raman spectroscopy.

scholarly journals All-Optical Modulation Technology Based on 2D Layered Materials

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 92
Author(s):  
Hongyan Yang ◽  
Yunzheng Wang ◽  
Zian Cheak Tiu ◽  
Sin Jin Tan ◽  
Libo Yuan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Communication Systems ◽  
Near Infrared ◽  
2D Materials ◽  
Optical Devices ◽  
Optical Systems ◽  
Optical Modulation ◽  
Wavelength Converter ◽  
Optical Modulators ◽  
All Optical

In the advancement of photonics technologies, all-optical systems are highly demanded in ultrafast photonics, signal processing, optical sensing and optical communication systems. All-optical devices are the core elements to realize the next generation of photonics integration system and optical interconnection. Thus, the exploration of new optoelectronics materials that exhibit different optical properties is a highlighted research direction. The emerging two-dimensional (2D) materials such as graphene, black phosphorus (BP), transition metal dichalcogenides (TMDs) and MXene have proved great potential in the evolution of photonics technologies. The optical properties of 2D materials comprising the energy bandgap, third-order nonlinearity, nonlinear absorption and thermo-optics coefficient can be tailored for different optical applications. Over the past decade, the explorations of 2D materials in photonics applications have extended to all-optical modulators, all-optical switches, an all-optical wavelength converter, covering the visible, near-infrared and Terahertz wavelength range. Herein, we review different types of 2D materials, their fabrication processes and optical properties. In addition, we also summarize the recent advances of all-optical modulation based on 2D materials. Finally, we conclude on the perspectives on and challenges of the future development of the 2D material-based all-optical devices.

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