Microstructural Characterization of SiGe Heterolayers

1991 ◽  
Vol 239 ◽  
Author(s):  
N. David Theodore ◽  
Peter Fejes ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Infrared Detectors ◽  
Field Effect ◽  
Strain Energy ◽  
Field Effect Transistors ◽  
Microstructural Characterization ◽  
Bipolar Transistors ◽  
Misfit Dislocations ◽  
Extended Defects

ABSTRACTSiGe is of interest for use in heterojunction-bipolar transistors, infrared detectors and field-effect transistors. In this study, graded SiGe heterolayers grown on Si, and heterolayers grown on SIMOX by CVD, were characterized using TEM. The graded-heterolayers consisted of ten layers of Si1-xGex on substrate silicon. Misfit dislocations were present at interfaces in the bottom 4–5 layers of the heterostructure. This conforms with predictions from qualitative strain-energy considerations. The greatest density of misfit dislocations was present at the Si1-xGex interface between the bottom two layers of the heterostructure. Dislocations were observed to extend out of the interface and up into the heterolayer structure. The defects were found to interact with interfaces in the structure and finally cease extending upwards towards the surface of the wafer. In addition to graded heterolayers, SiGe heterolayers grown on SIMOX were also investigated. The structures consisted of epi-silicon grown on a Si/Si1-xGex superlattice which was in turn grown on a Si/SiO2 (SIMOX) structure. The behavior of defects in the layers was of interest. TEM characterization showed a large density of extended-defects present in the layers. Dislocations were observed to originate at the SIMOX oxide/Si interface, propagate up through the SiGe superlattice and into the epi-Si layer. Some dislocations were found to interact with the SiGe superlattice and cease propagating up towards the top of the wafer. SiGe superlattices with a higher concentration of Ge are more effective in reducing defect propagation towards the surface of the wafer.

Microstructural Characterization of High-Pressure Oxidized Si1-x Gex /Si Heterolayers

1992 ◽  
Vol 280 ◽  
Author(s):  
N. David Theodore ◽  
Gordon Tam
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Atmospheric Pressure ◽  
High Pressures ◽  
Microstructural Characterization ◽  
Bipolar Transistors ◽  
Pure Silicon ◽  
Device Structures ◽  
Microstructural Behavior ◽  
Very High

ABSTRACTSiGe alloys have recently been of interest for fabrication of heterojunction bipolar transistors using pre-existing or modified silicon-processing technology. These devices are faster than devices using pure silicon. Because of the interest in developing SiGe device structures, various elements of processing relevant to fabrication of the devices are being investigated. One such element has been the use of thermal oxidation for isolation of SiGe devices. Utilization of the technique requires an understanding of oxidation behavior of SiGe layers under a variety of oxidation conditions. Past studies in the literature have investigated the oxidation of SiGe at atmospheric pressure or at very high pressures (∼650–1300 atmospheres). The present study investigates the wet-oxidation of SiGe structures at intermediate pressures (∼25 atmospheres) and temperatures (∼750°C). Unlike atmospheric oxidation, most of the Ge (from SiGe) remains in the oxidized silicon (SiO2) in the form of GeO2. Occasional segregation of Ge to the oxidizing interface is noted. The microstructural behavior of partially and entirely oxidized structures is presented.

Behavior of Damage in Selectively Implanted SiGe/Si

1993 ◽  
Vol 319 ◽  
Author(s):  
N. David Theodore ◽  
Gordon Tam ◽  
Jim Whitfield ◽  
Jim Christiansen ◽  
John Steele
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
High Speed ◽  
Critical Thickness ◽  
Bipolar Transistors ◽  
Electrical Performance ◽  
Misfit Dislocations ◽  
Extended Defects ◽  
Dislocation Loops ◽  
And Behavior ◽  
Dislocation Sources

AbstractEpitaxial SiGe/Si layers are being extensively investigated for use in base regions of high-speed heterojunction bipolar-transistors (HBTs). Extended defects can be formed in SiGe/Si layers by ion-implantation. Defects, once formed in the layers, can negatively impact electrical performance and also future reliability of the HBTs. The present study investigates the interaction between selective-implant damage and strained SiGe/Si layers of sub-critical thickness. Implant-damage is observed to form dislocation-sources at the edges of implanted regions in SiGe/Si heterolayers. The dislocation sources produce glide dislocation loops. Segments of these loops glide down to SiGe/Si interfaces causing misfit dislocations to arise at interfaces in the heterolayers. Misfitdislocations are formed in directions parallel to and perpendicular to the <110> edge of the implanted region. Dislocations propagate out to a distance of ∼100-150 nm past the edge of the implant in the case of Si0.9Ge0.1/Si layers of sub-critical thickness. The origin and behavior of these defects is discussed.

TEM characterization of SiGe heterolayers grown on SIMOX

1991 ◽  
Vol 49 ◽  
pp. 886-887
Author(s):  
N. David Theodore ◽  
Peter Fejes ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Vapor Deposition ◽  
Infrared Detectors ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Silicon On Insulator ◽  
Strain Fields ◽  
Device Structures ◽  
Defect Densities

SiGe heterolayers are of interest for use in heterojunction transistors, infrared detectors and field-effect transistors. SIMOX (Separation of silicon by IMplanted OXygen) is useful for fabrication of silicon-on-insulator (SOI) structures (electrically isolated from the substrate). SIMOX could potentially be used for isolation of SiGe structures from the substrate. Epitaxial-Si grown on SIMOX (required for some device structures) can have grown-in dislocations that arise due to STMOX-related damage. If SiGe heterolayers were grown on silicon, dislocations could interact with the strain fields associated with the SiGe layers. Such interaction could possibly lead to a reduction in defect densities in upper layers of the structures. In the present study, SiGe heterolayers grown on SIMOX by chemical vapor deposition were characterized using TEM. The structures consisted of epi-silicon grown on a Si/Sii-xGex superlattice which was in turn grown on a Si/SiO2 (SIMOX) structure. The behavior of defects in the structures was of interest.

TEM evaluation of graded SixGe1-x heterolayers

1991 ◽  
Vol 49 ◽  
pp. 894-895
Author(s):  
N. David Theodore ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Gas Flow ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Dark Field ◽  
Bipolar Transistors ◽  
Structural Quality ◽  
Weak Beam ◽  
Transmission Electron ◽  
And Behavior

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.

Fabrication and Characterization of GaN-based Nanostructure Field Effect Transistors

2021 ◽  
pp. 108079
Author(s):  
Dong-Hyeok Son ◽  
Terirama Thingujam ◽  
Quan Dai ◽  
Jeong-Gil Kim ◽  
Sorin Cristoloveanu ◽  
...  
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
Fabrication And Characterization
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