STUDY ON AlSb POLYCRYSTALLINE THIN FILMS PREPARED BY VACUUM CO-EVAPORATION

2011 ◽  
Vol 25 (13) ◽  
pp. 1747-1755 ◽  
Author(s):  
HUIJIN SONG ◽  
LILI WU ◽  
JIAGUI ZHENG ◽  
LIANGHUAN FENG ◽  
ZHI LEI ◽  
...  
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Open Circuit ◽  
Photovoltaic Devices ◽  
Amorphous Thin Films ◽  
Optical Absorption Measurement ◽  
Heating And Cooling ◽  
Polycrystalline Thin Films ◽  
Bandgap Semiconductors ◽  
P Type

In this paper, the AlSb polycrystalline thin films were prepared by vacuum co-evaporation technology and their structural, optical and electrical properties have been studied. XRD results showed that the as-deposited AlSb amorphous thin films transformed to polycrystalline state after annealed in vacuum at temperatures higher than 540°C. The process of phase change was observed to depend on the annealing temperature and the film composition. Some irreversible changes took place in the annealed films during the measurement of the temperature dependence of the film conductance. The conductance activation energy of the film was 0.132 and 0.32 eV during the heating and cooling process, respectively, which suggests the decrease of Sb vacancies in the AlSb film after the heating. Hall effect and optical absorption measurement showed that the AlSb polycrystalline thin films were p-type, indirect bandgap semiconductors with absorption coefficient higher than 8 × 104 cm -1. TCO/CdS/AlSb photovoltaic devices with the local open circuit voltage of over 200 mV have been fabricated.

scholarly journals Properties of Arsenic–Doped ZnTe Thin Films as a Back Contact for CdTe Solar Cells

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3706 ◽  
Author(s):  
Ochai Oklobia ◽  
Giray Kartopu ◽  
Stuart J. C. Irvine
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Open Circuit ◽  
Activation Process ◽  
Back Contact ◽  
Contact Activation ◽  
Doping Density ◽  
Cdte Solar Cells ◽  
Absorber Doping ◽  
P Type

As-doped polycrystalline ZnTe layers grown by metalorganic chemical vapor deposition (MOCVD) have been investigated as a back contact for CdTe solar cells. While undoped ZnTe films were essentially insulating, the doped layers showed significant rise in conductivity with increasing As concentration. High p-type carrier densities up 4.5 × 1018 cm−3 was measured by the Hall-effect in heavily doped ZnTe:As films, displaying electrical properties comparable to epitaxial ZnTe single crystalline thin films in the literature. Device incorporation with as-deposited ZnTe:As yielded lower photovoltaic (PV) performance compared to reference devices, due to losses in the open-circuit potential (VOC) and fill factor (FF) related to reducing p-type doping density (NA) in the absorber layer. Some minor recovery observed in absorber doping following a Cl-free post–ZnTe:As deposition anneal in hydrogen at 420 °C contributed to a slight improvement in VOC and NA, highlighting the significance of back contact activation. A mild CdCl2 activation process on the ZnTe:As back contact layer via a sacrificial CdS cap layer has been assessed to suppress Zn losses, which occur in the case of standard CdCl2 anneal treatments (CHT) via formation of volatile ZnCl2. The CdS sacrificial cap was effective in minimising the Zn loss. Compared to untreated and non-capped, mild CHT processed ZnTe:As back contacted devices, mild CHT with a CdS barrier showed the highest recovery in absorber doping and an ~10 mV gain in VOC, with the best cell efficiency approaching the baseline devices.

Chalcogenide Glass Thin Films for Nanodipole Junctionless Photovoltaics

2011 ◽  
Vol 1322 ◽  
Author(s):  
Sakina Junaghadwala ◽  
Daniel G. Georgiev ◽  
Victor G. Karpov ◽  
Rossen Todorov ◽  
Nanke Jiang
Keyword(s):  
Thin Films ◽  
Chalcogenide Glass ◽  
Open Circuit Voltage ◽  
High Vacuum ◽  
Practical Interest ◽  
Open Circuit ◽  
Photovoltaic Devices ◽  
Scanning Calorimetry ◽  
New Type ◽  
Initial Results

ABSTRACTWe examine the potential of Bi-Ge-Se chalcogenide glass films as materials for a new type of photovoltaic devices, referred to as junctionless nanodipole PV. Glasses of a chemical composition providing a significant optical absorption were synthesized in quartz ampoules from high-purity Bi, Ge, and Se elements by a conventional melt quenching technique. This material was then used to deposit thin films with different thicknesses on various substrates by thermal evaporation under high-vacuum conditions. The original bulk glasses and the films were characterized by electron microscopy with EDS, XRD, Raman spectroscopy, differential scanning calorimetry, and spectrophotometry. Open-circuit voltage (Voc) readings under incandescent illumination were obtained from the as-deposited and annealed films. Results from this characterization work are presented and discussed. Although the efficiency of nanodipole PV material structures, based on this material remains of no practical interest, our initial results indicate a possible path for the implementation of the nanodipole PV concept.

Thermoelectric Module of P-Type Ca-Co-O/N-Type ZnO Thin Films

2012 ◽  
Vol 622-623 ◽  
pp. 726-733 ◽  
Author(s):  
Weerasak Somkhunthot ◽  
Nuwat Pimpabute ◽  
Tosawat Seetawan
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Power Factor ◽  
Electrical Power ◽  
Thermoelectric Module ◽  
Preliminary Test ◽  
Internal Resistance ◽  
Open Circuit ◽  
P Type

Thin films thermoelectric module fabricated by pulsed-dc magnetron sputtering system using Ca3Co4O9(p-type) and ZnO (n-type) targets of 60 mm diameter and 2.5 mm thickness, which were made from powder precursor, and obtained by solid state reaction. Thin films of p-Ca-Co-O (Seebeck coefficient = 143.85 µV/K, electrical resistivity = 4.80 mΩm, power factor = 4.31 µW/m K2) and n-ZnO (Seebeck coefficient =229.24 µV/K, electrical resistivity = 5.93 mΩm, power factor = 8.86 µW/m K2) were used to make a thermoelectric module, which consist of four pairs of legs connected by copper electrodes (0.5 mm thickness, 3.0 mm width, and 3.0-8.0 mm length). Each leg is 3.0 mm width, 20.0 mm length, and 0.44 µm thickness on a glass substrate of 1.0 mm thickness in dimension 25.0x50.0 mm2. For preliminary test, a module was used to thermoelectric power generation. It was found that the open circuit voltage increased with increasing temperature difference from 3 mV at 5 K up to 20 mV at 78 K. The internal resistance of a module reached a value of 14.52 MΩ. This test indicated that a module can be generated the electrical power. Therefore, it can be used as an important platform for further thin films thermoelectric module research.

scholarly journals Chalcogenide glass-ceramic with self-organized heterojunctions: application to photovoltaic solar cells

2018 ◽  
Vol 9 ◽  
pp. 3 ◽  
Author(s):  
Xianghua Zhang ◽  
Ilia Korolkov ◽  
Bo Fan ◽  
Michel Cathelinaud ◽  
Hongli Ma ◽  
...  
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Chalcogenide Glass ◽  
Glass Ceramic ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Iodine Doping ◽  
P Type ◽  
Photovoltaic Solar Cells

In this work, we present for the first time the concept of chalcogenide glass-ceramic for photovoltaic applications with the GeSe2–Sb2Se3–CuI system. It has been demonstrated that thin films, deposited with the sputtering technique, are amorphous and can be crystallized with appropriate heat treatment. The thin film glass-ceramic behaves as a p-type semiconductor, even if it contains p-type Cu2GeSe3and n-type Sb2Se3. The conductivity of Sb2Se3has been greatly improved by appropriate iodine doping. The first photovoltaic solar cells based on the association of iodine-doped Sb2Se3and the glass-ceramic thin films give a short-circuit current density JSCof 10 mA/cm2and an open-circuit voltage VOCof 255 mV, with a power conversion efficiency of about 0.9%.

Study of the Defect Levels and Interface Properties of CdTe and CdS Polycrystalline Thin Films

1991 ◽  
Vol 238 ◽  
Author(s):  
F. Abou-Elfotouh ◽  
S. Ashour ◽  
S. A. Alkuhaimi ◽  
J. Zhang ◽  
D. J. Dunlavy ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Deep Trap ◽  
Cdte Film ◽  
Interface States ◽  
Polycrystalline Thin Films ◽  
Deviation From Stoichiometry ◽  
Electrochemically Deposited ◽  
Defect Levels ◽  
P Type

ABSTRACTThe properties (electrical and structural) and the defect levels dominating cadmium telluride (CdTe) films prepared by radio frequency (rf) planar magnetron sputtering, and electrochemical deposition have been determined and compared. The properties of the deposited CdTe film and the behavior of its interface with cadmium sulfide (CdS) depend strongly on the method of depositing the CdTe film, and on postdeposition heat treatments. These treatments determine various parameters crucial to the device performance, including the type and concentration of the dominant defects, interface states, and deep trap levels. Photoluminescence (PL) emission from p-type CdTe polycrystalline thin films and single crystals is reported at low temperatures (9–50 K) as well as at room temperature. The room temperature PL peak at 1.58 eV due to band-to-band recombination was observed for the first time in polycrystalline thin films. The peak location of the exciton emission is indicative of the structure perfection of the film, which is also related to the deviation from stoichiometry. The as-grown polycrystalline films are composed of a close-packed array of preferentially oriented (the [100], [110], and [111] axes aligned perpendicular to the substrate) single-crystal grains of a size in the range of 0.25–2.0 μm for the electrochemically deposited films (E-film) and 0.3–4.0 μm for rf sputtered material (rf-film). The resistivity of the heat treated E-film was substantially lower than that of the rf-film (ρ = 1.0–5.0 and 300–500 Ωcm). The performance of the CdS/(E-CdTe) devices is limited by deep levels, while the performance of die rf-CdTe device is affected by a high density of interface states.

scholarly journals Phosphorous doped p-type MoS2 polycrystalline thin films via direct sulfurization of Mo film

AIP Advances ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 025009 ◽  
Author(s):  
Tomohiro Momose ◽  
Atsushi Nakamura ◽  
Moraru Daniel ◽  
Masaru Shimomura
Keyword(s):  
Thin Films ◽  
Polycrystalline Thin Films ◽  
P Type

NITRIDE BASED SCHOTTKY-BARRIER PHOTOVOLTAIC DEVICES

2007 ◽  
Vol 1040 ◽  
Author(s):  
Balakrishnam R Jampana ◽  
Omkar K Jani ◽  
Hongbo Yu ◽  
Ian T Ferguson ◽  
Brian E McCandless ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Annealing Temperature ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Schottky Contact ◽  
Open Circuit ◽  
Photovoltaic Devices ◽  
Current Increase ◽  
Uv Illumination

AbstractSchottky-barrier photovoltaic devices are fabricated by selective metal deposition on p-GaN. A 1.25 V open-circuit voltage is observed for the best device. Devices were optimized by annealing in forming gas at temperatures ranging from 550°C to 700°C. Annealing time and forming gas flow rate are used to control the metal-semiconductor Schottky barrier formation. Optimum fabrication parameters are achieved based on photovoltaic response from the devices under UV illumination. Barrier heights (0.47 eV - 0.49 eV) were used as basis to compare the device response. The Schottky-barrier height is very sensitive to processing conditions, for example a 2.5% increase in barrier height is observed when Schottky contact annealing temperature is changed from 600 °C to 650 °C. Under UV illumination, the open-circuit voltage and short-circuit current increase with increasing annealing temperature while the series resistance decreases under such conditions.

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