Author: James Robert DoylePublisher:
ISBN:
Category : Amorphous semiconductors
Languages : en
Pages : 400
Book Description
Deposition Kinetics of Hydrogenated Amorphous Silicon and Silicon-germanium Thin Films
Author: James Robert DoylePublisher:
ISBN:
Category : Amorphous semiconductors
Languages : en
Pages : 400
Book Description
High Growth Rate Deposition of Hydrogenated Amorphous Silicon-germanium Films and Devices Using ECR-PECVD
Author: Yong LiuPublisher:
ISBN:
Category :
Languages : en
Pages : 170
Book Description
Hydrogenated amorphous silicon germanium (a-SiGe:H) films and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with small amount of H2, was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, and quantum efficiency were characterized during the process of pursuing good materials. High-quality material was successfully fabricated with the ECR-PECVD technique at high growth rates. The device we made with 1.47 eV band gap has a fill factor of 64.5%. With the graded band gap and graded doping techniques, 70% fill factor was achieved when the band gap was graded from 1.75 to 1.47 eV. We also got 68% fill factor with the band gap graded form 1.75 to 1.38 eV.
High Growth Rate Deposition of Hydrogenated Amorphous Silicon-Germanium Films and Devices Using ECR-PECVD.
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Hydrogenated amorphous silicon germanium films (a-SiGe:H) and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large-scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert-gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. Preferential attachment of hydrogen to silicon, clustering of Ge and Si, and columnar structure and buried dihydride radicals make the film intolerably bad. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with a small amount of H[sub 2], was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, I-V curve, and quantum efficiency were characterized during the process of pursuing good materials. The microstructure of the a-(Si, Ge):H material was probed by Fourier-Transform Infrared spectroscopy. They found that the advantages of using helium as the main plasma species are: (1) high growth rate--the energetic helium ions break the reactive gas more efficiently than hydrogen ions; (2) homogeneous growth--heavy helium ions impinging on the surface promote the surface mobility of the reactive radicals, so that heteroepitaxy growth as clustering of Ge and Si, columnar structure are reduced; (3) surface hydrogen removal--heavier and more energetic helium ions break the Si-H much easier than hydrogen ions. The preferential attachment of Si-H to Ge-H is reduced. They also found that with the small amount of hydrogen put into the plasma, the superior properties of a-(Si, Ge):H made from pure hydrogen dilution plasma were still maintained. These hydrogen ions help to remove the subsurface weakly bonded hydrogen and buried hydrogen. They also help to passivate the Ge-dangling bond.
Plasma Deposition of Amorphous Silicon-Based Materials
Author: Pio CapezzutoPublisher: Elsevier
ISBN: 0080539106
Category : Science
Languages : en
Pages : 339
Book Description
Semiconductors made from amorphous silicon have recently become important for their commercial applications in optical and electronic devices including FAX machines, solar cells, and liquid crystal displays. Plasma Deposition of Amorphous Silicon-Based Materials is a timely, comprehensive reference book written by leading authorities in the field. This volume links the fundamental growth kinetics involving complex plasma chemistry with the resulting semiconductor film properties and the subsequent effect on the performance of the electronic devices produced. Focuses on the plasma chemistry of amorphous silicon-based materials Links fundamental growth kinetics with the resulting semiconductor film properties and performance of electronic devices produced Features an international group of contributors Provides the first comprehensive coverage of the subject, from deposition technology to materials characterization to applications and implementation in state-of-the-art devices
Properties of Hydrogenated Amorphous Silicon-germanium Alloys Deposited by Dual Target Reactive Magnetron Sputtering
Author: Samuel J. LevangPublisher:
ISBN:
Category : Silicon alloys
Languages : en
Pages : 36
Book Description
Hydrogenated amorphous silicon-germanium alloy thin films (a-Si1-xGex:H) were deposited using reactive magnetron sputtering. Dual targets of silicon and germanium were sputtered in an argon + hydrogen atmosphere using RF excitation. Films with x = 0.4 were deposited as a function of substrate temperature and hydrogen partial pressure, and were evaluated by dark and photoconductivity, infrared absorption, and optical transmission. Photosensitivity reached a maximum value of about 4500 between 150 and 200°C. Using the stretching modes in the region of 2000 cm-1, the hydrogen bonding was characterized in terms of the preferential attachment ratio (PA), which represents the ratio between H bonded to Si and H bonded to Ge. The PA shows a systematic increase with increasing temperature, generally independent of hydrogen partial pressure. The interplay between thermodynamic and kinetics effects in determining PA and film quality is discussed.
Deposition and Characterization of Hydrogenated Amorphous Silicon, Microcrystalline Silicon and Silicon Based Alloy Thin Films
Author: Cheng WangKinetic Roughening During Hot-wire Chemical Vapor Deposition of Hydrogenated Amorphous Silicon
Author: Brent Andrew SperlingPublisher:
ISBN:
Category :
Languages : en
Pages : 127
Book Description
Despite the widespread use of hydrogenated amorphous silicon (a-Si:H), the fundamental surface processes during film growth are not well understood. One approach to studying these mechanisms is to analyze the surface morphology that results from their action. In this dissertation, hot-wire chemical vapor deposition is used to deposit a-Si:H thin films. Both post-deposition atomic force microscopy (AFM) and in situ spectroscopic ellipsometry (SE) are used to characterize the surface morphology and its dynamics. Results of this work indicate that the surface morphology is shaped by geometric shadowing of growth particles and thermally-activated smoothening mechanisms. For films grown at low temperature, the local slope of the surface is found to exhibit power law scaling with time that is consistent with anomalous roughening behavior also observed in models that include shadowing. A temperature-dependent transition in roughening behavior is observed, and an activation energy is extracted that agrees with previous estimates for SiH3 surface diffusion. Additionally, a-Si:H grown on rough substrates is examined. Smoothening at short lateral length scales is observed simultaneously with global roughening. Behavior is found to generally agree with deterministic models in the literature. This work also explores the difference between SE and AFM in how roughness is measured. Rayleigh-Rice theory (vector perturbation theory) is used to calculate ellipsometric data that is subsequently compared to the usual method of using an effective medium layer to approximate roughness. SE measurements are found to critically depend on both the vertical extent of roughness and the root-mean-squared slope of the surface.
Plasma Deposition of Amorphous Silicon-based Materials
Author: Giovanni BrunoPublisher:
ISBN: 9780121379407
Category : Science
Languages : en
Pages : 324
Book Description
Semiconductors made from amorphous silicon have recently become important for their commercial applications in optical and electronic devices including FAX machines, solar cells, and liquid crystal displays. Plasma Deposition of Amorphous Silicon-Based Materials is a timely, comprehensive reference book written by leading authorities in the field. This volume links the fundamental growth kinetics involving complex plasma chemistry with the resulting semiconductor film properties and the subsequent effect on the performance of the electronic devices produced. Key Features * Focuses on the plasma chemistry of amorphous silicon-based materials * Links fundamental growth kinetics with the resulting semiconductor film properties and performance of electronic devices produced * Features an international group of contributors * Provides the first comprehensive coverage of the subject, from deposition technology to materials characterization to applications and implementation in state-of-the-art devices
Hydrogenated Amorphous Silicon
Author: H. Neber-AeschbacherPublisher: Trans Tech Publications Ltd
ISBN: 3035706603
Category : Technology & Engineering
Languages : en
Pages : 1080
Book Description
Ever since the work of W.E. Spear and P.G. LeComber had proved that an amorphous semiconductor could indeed also be substitutionally doped, research in the respective field has seen an nearly unprecedented development. The role of hydrogen in atomic and electronic structure as well as in the doping mechanism remains an outstanding problem addressed both to theoreticians and experimentalists, and a highly interesting challenge both to the scientist as well as the engineer.
Plasma Enhanced Chemical Vapor Deposition of Hydrogenated Amorphous Silicon Thin Films with Nanocrystalline Inclusions
Author: Siri Suzanne ThompsonPublisher:
ISBN:
Category :
Languages : en
Pages : 138
Book Description