Author: Electrochemical SocietyPublisher:
ISBN:
Category : Electrochemistry
Languages : en
Pages : 918
Book Description
GaAs passivation by LF-PECVD silicon nitride deposition
Author: Abdelatif JaouadPublisher: Omniscriptum
ISBN: 9786131581618
Category :
Languages : fr
Pages : 164
Book Description
Les performances de plusieurs dispositifs fabriqués sur des matériaux III-V sont lourdement affectées par la grande densité des états de surface qui sont localisés au voisinage du milieu de la bande interdite (niveaux profonds). Ces états électroniques sont responsables du pinning du niveau de Fermi, et empèchent l'émergence d'une technologie MOS (Métal- Oxyde-Semiconducteur) viable à ce jour sur ces matériaux. Les niveaux profonds limitent aussi les performances des dispositifs photoniques. Dans ce document, nous démontrons que la déposition du nitrure de silicium par LF-PECVD (Low frequency plasma enhanced vapor deposition), assure une passivation efficace du GaAs. Le modèle proposé pour expliquer le fort potentiel de cette technique, est basé sur le fait que les ions hydrogène fournies par le silane et l'ammoniac peuvent suivre le signal RF et traverser la gaine du plasma et bombarder la surface de GaAs. Cette hydrogénation permet de désoxyder la surface de GaAs et réduit l'arsenic élémentaire, ce qui permet de lever le pinning du niveau de Fermi. Ce modèle a été validé par des analyses physico-chimiques.
Thermal Stability of Plasma-enhanced Chemical Vapor Deposition Silicon Nitride Passivation on AlGaN/GaN High-electron-mobility Transistors
Author: Minh-Trang Teresa HaPublisher:
ISBN:
Category :
Languages : en
Pages : 43
Book Description
AlGaN/GaN HEMTs are the most promising high power switching devices. The material properties of III-nitrides are exceptionally better than that of Si and GaAs. GaN-based devices have been recorded to have higher operating temperatures and higher breakdown field due to the wide bandgap. AlGaN/GaN heterostructures forms 2DEG without doping due to the spontaneous polarization. The performance and reliability of AlGaN/GaN HEMTs are dependent on the structure of the AlGaN/GaN heterostructures. Surface passivation has been proven to improve the 2DEG conductivity and device performance. 20 nm of plasma-enhanced chemical vapor deposition (PECVD) SiN was deposited on AlGaN/GaN HEMTs, and the PECVD SiN passivated sample demonstrated higher carrier concentration of 9.88 ? 1012 cm-2 compared to the un-passivated sample, 8.08 ? 1012 cm-2. High temperature annealing is an important processing step in the fabrication of the devices, and the effects have shown to improve the DC and RF performance. High temperature annealing may affect the structure and the 2DEG conductivity. The annealing effects modifies the AlGaN layer and the AlGaN/GaN interface. Herein, we present the a study on the thermal stability of the PECVD SiN passivation layer on AlGaN/GaN HEMT structures at high temperature anneals. High-resolution x-ray diffraction (HRXRD) measurements were used to investigate the strain of AlGaN layer, and Hall measurements were used to investigate the 2DEG conductivity. PECVD SiN passivated and un-passivated AGaN/GaN HEMTs structure underwent high temperature thermal anneals for 30 minutes in N2. The starting temperature of the annealing is 400?C with step of 50?C until degradation. Degradation was determined through Hall sheet resistivity and mobility measurements. The ending annealed temperature is 1000 ?C and 700 ?C for passivated and control samples, respectively. From no anneal to degradation temperature, the 2DEG conductivity dropped by 15% and 34% for passivated and un-passivated samples, respectively. The HRXRD measurements found the change in-plane strain of the AlGaN layer after high temperature anneals. Higher in-plane strain showed higher 2DEG conductivity. In-plane strain from no anneal to degradation temperature dropped from 2% and 7% for passivated and un-passivated samples, respectively. Therefore, the passivated sample demonstrated to be more stable at high temperatures. The SiN passivation layer adds tensile stress to the AlGaN layer thus increased the piezoelectric effect and 2DEG conductivity.
Effective Passivation of the Low Resistivity Silicon Surface by a Rapid Thermal Oxide/PECVD Silicon Nitride Stack and Its Application to Passivated Rear and Bifacial Si Solar Cells
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 5
Book Description
A novel stack passivation scheme, in which plasma silicon nitride (SiN) is stacked on top of a rapid thermal SiO2 (RTO) layer, is developed to attain a surface recombination velocity (S) approaching 10 cm/s at the 1.3 [Omega]-cm p-type (100) silicon surface. Such low S is achieved by the stack even when the RTO and SiN films individually yield considerably poorer surface passivation. Critical to achieving low S by the stack is the use of a short, moderate temperature anneal (in this study 730 C for 30 seconds) after film growth and deposition. This anneal is believed to enhance the release and delivery of atomic hydrogen from the SiN film to the Si-SiO2 interface, thereby reducing the density of interface traps at the surface. Compatibility with this post-deposition anneal makes the stack passivation scheme attractive for cost-effective solar cell production since a similar anneal is required to fire screen-printed contacts. Application of the stack to passivated rear screen-printed solar cells has resulted in V{sub oc}'s of 641 mV and 633 mV on 0.65 [Omega]-cm and 1.3 [Omega]-cm FZ Si substrates, respectively. These V{sub oc} values are roughly 20 mV higher than for cells with untreated, highly recombinative back surfaces. The stack passivation has also been used to form fully screen-printed bifacial solar cells which exhibit rear-illuminated efficiency as high as 11.6% with a single layer AR coating.
GaAs Surface Passivation for Device Applications
Author: C. L. AndersonPublisher:
ISBN:
Category :
Languages : en
Pages : 21
Book Description
This report describes the initial stages of a program to develop deposited dielectrics for GaAs device applications. Three applications of the dielectrics are being investigated: (1) isolation of control electrodes, (2) passivation of the GaAs surface, and (3) encapsulation of completed circuits. The dielectrics being studied include silicon oxynitride; mixtures of silicon nitrode and germanium nitride; and mixtures of silicon dioxide, gallium oxide, and aluminum oxide. Deposition techniques being employed are pyrolytic chemical vapor deposition, plasma-enhanced deposition, and photochemical deposition. This report describes the apparatus being used for this program and the chemical analysis of preliminary films deposited. No interface state measurements are reported. (Author).
Donor Neutralization in GaAs After Plasma Silicon Nitride Deposition
Author: Karen L. SeawardPublisher:
ISBN:
Category : Metal oxide semiconductors, Complementary
Languages : en
Pages : 15
Book Description
Abstract: "Loss of conductance has been observed in Si-doped GaAs after plasma silicon nitride deposition in a 2.45 GHz ECR reactor and in a 30 kHz parallel-plate reactor, but not in a 13.56 MHz parallel-plate reactor. Based on the temperature at which conductance is restored in test structures subjected to a variety of plasmas, observation of atomic hydrogen in the plasmas by optical emission, and SIMS measurement of hydrogen in the test structures, the loss of conductance appears to be from formation of the hydrogen-silicon complex. The extent of neutralization correlates with an abundance of atomic hydrogen in the plasmas and the nitride deposition rate. When the deposition rate is high, the GaAs surface is protected quickly and donor neutralization is minimized."
Investigation of Silicon Surface Passivation by Silicon Nitride Film Deposition ....
Author: Passivation and Gating of GaAs and Si Surfaces Using Pseudomorphic Structures
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 30
Book Description
During the first quarter we began work directed at the Silicon- Gallium arsenide interface formation. This work encompasses the in situ cleaning process and the Silicon deposition process. Advances have been made in the GaAs in situ cleaning. The reasons for the advances, recognition of Silicon dioxide deposition byproduct residue and additions of a load lock to the system, are described. Work towards improving the pseudomorphic Si deposition is also described. During the second quarter work continued on the Gallium arsenide- Silicon interface formation. We had noted improvements in the low temperature Silicon epitaxial deposition through the incorporation of hydrogen in the deposition environment. Also we noted improvements in the Silicon deposition through the use of lower pressure conditions. The results of the use of Metal- insulator Semiconductor results obtained on both p-type and n-type Gallium arsenide-Silicon with partially optimized processing are described. These Silicon deposition conditions for Metal-insulator Semiconductor structure formation are described. During the third and fourth quarters work again continued on the Gallium-arsenide-Silicon interface formation. During this period a series of experiments was performed to evaluate the effects of processing conditions on the p-type GaAs MIS structure. MIS, Pseudomorphic Si on GaAs in Situ GaAs Cleaning, Passivation, Semiconductors, Gating technology.
Bulk and Surface Passivation by Silicon Nitride Grown by Remote Microwave PECVD
Author: W. J. SoppeECR Plasma Synthesis of Silicon Nitride Films on GaAs and InSb
Author: Extended Abstracts
Author: Electrochemical SocietyPublisher:
ISBN:
Category : Electrochemistry
Languages : en
Pages : 918
Book Description