High Spatial Resolution Thermal Conductivity investigation of SiC Wafers

2001 ◽  
Vol 680 ◽  
Author(s):  
D.I. Florescu ◽  
Fred H. Pollak ◽  
G.R. Brande ◽  
B.E. Landini ◽  
A.D. Salant
Keyword(s):  
Thermal Conductivity ◽  
High Power ◽  
Defect Density ◽  
Depth Resolution ◽  
Scanning Thermal Microscopy ◽  
Roughness Effects ◽  
Semiconductor Electronics ◽  
Device Applications ◽  
Absolute Measurements ◽  
Spatial Depth

ABSTRACTSilicon carbide (SiC) is a material with very attractive properties for high power/high temperature electronic devices. Its mechanical strength, high thermal conductivity ( κ), large bandgap, and extreme chemical inertness are a few of the characteristics making SiC interesting for semiconductor electronics. Due to the significant head load generated over large areas in high power devices, it is desirable forthe thermal properties of the substrate to be uniform and optimal. Scanning thermal microscopy (SThM), which provides nondestructive, absolute measurements of the thermal conductivity with a spatial/depth resolution in the 2-3 μm range, was used to examine the room temperature κ as a function of position of four 2” diameter SiC wafers. Wafers of 4H and 6H polytype were fabricated with carrier concentrations in the(1-3)×1018 cm−3 and (6-9)×1017 cm−3 ranges, respectively. A radial distribution of the thermal conductivity was determined for all the investigated samples. For a radius r < r1 (r1 ∼ 0.3”) and r > r2 (r2 ∼ 0.7”) highest thermal conductivity values were measured in the range of (3.8-3.9) W/cm-K, comparable to the highest κ reported for this material [D. Morelli et al., Inst. Phys. Conf. Ser. 137, 313 (1993); E.A. Burgemeister,.et al., J. Appl. Phys. 50, 5790 (1979)]. For r1 < r < r2 the thermal conductivity drops to about (2.85-3.25) W/cm-κinterval. Atomic force microscopy (AFM) investigation revealsthat the influence of surface roughness effects on κ is negligible. The κ dip may arise from a higher basal plane defect density in this region that could be associated with the presence of super screw dislocations, or “micropipes” [M. Dudley et al., J. Phys. D: Appl. Phys. 28, A63 (1995)]. The implications of these findings for device applications and design are considered.

Plasma-Induced Effects on The Thermal Conductivity of Hydride Vapor Phase Epitaxy Grown n-GaN/Sapphire (0001)

2000 ◽  
Vol 639 ◽  
Author(s):  
D.I. Florescu ◽  
Fred H. Pollak ◽  
William B. Lanfor ◽  
Farid Khan ◽  
I. Adesida ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Vapor Phase ◽  
High Power ◽  
Gas Flow ◽  
Depth Resolution ◽  
Vapor Phase Epitaxy ◽  
Hydride Vapor Phase Epitaxy ◽  
Processing Parameter ◽  
Ar Gas ◽  
Spatial Depth

ABSTRACTWe have measured high spatial/depth resolution (2-3 [.proportional]m) thermal conductivity (κk) at 300K before and after plasma-induced effects on a series of n-GaN/sapphire (0001) samples fabricated by hydride vapor phase epitaxy (HVPE) using a ThermoMicroscope'as scanning thermal microscope (SThM). The sample thicknesses were 50 ± 5 [.proportional]m and the carrier concentrations ~ 8 × 1016 cm-3, as determined by Hall effect measurements. The thermal conductivity before treatment was found to be in the 1.70 – 1.75 W/cm-K range, similar to that previously reported for HVPE material with this carrier concentration and thickness [D. I. Florescu et al., J. Appl. Phys. 88, 3295 (2000)]. The samples were processed under constant Ar gas flow and pressure fora fixed period of time (5 min). The only variable processing parameter was the DC bias voltage (125 – 500 V). After the initial 125 V procedure κ exhibited a decrease linear in the DC voltage in the investigated range. At 125 V the thermal conductivity was only slightly less (κ ~ 1.65 W/cm-K) than the untreated case. κ had dropped to ~ 0.3 W/cm-K for the 500 V situation. The implications of these results for device applications in the area of high power opto-electronics and high power electronics will be discussed.

The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

1985 ◽  
Vol 43 ◽  
pp. 154-157
Author(s):  
A.J. Tousimis
Keyword(s):  
Ion Beam ◽  
Depth Resolution ◽  
Sample Surface ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Electrons And Ions ◽  
Spatial Depth ◽  
Minimum Surface Area ◽  
Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

scholarly journals Thermal conductivity performance of nanoporous plate for high-power LED lighting and power electronics

2019 ◽  
Vol 1309 ◽  
pp. 012016
Author(s):  
A D Kurilov ◽  
V V Belyaev ◽  
K D Nessemon ◽  
E D Besprozvannyi ◽  
A O Osin ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Power Electronics ◽  
High Power ◽  
Led Lighting ◽  
High Power Led

Adhesive penetration of wood cell walls investigated by scanning thermal microscopy (SThM)

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Johannes Konnerth ◽  
David Harper ◽  
Seung-Hwan Lee ◽  
Timothy G. Rials ◽  
Wolfgang Gindl
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Surface Temperature ◽  
Cell Walls ◽  
Adhesive Contact ◽  
Wood Adhesive ◽  
Bond Line ◽  
Scanning Thermal Microscopy ◽  
Thermal Probe ◽  
Thermal Microscopy

Abstract Cross sections of wood adhesive bonds were studied by scanning thermal microscopy (SThM) with the aim of scrutinizing the distribution of adhesive in the bond line region. The distribution of thermal conductivity, as well as temperature in the bond line area, was measured on the surface by means of a nanofabricated thermal probe offering high spatial and thermal resolution. Both the thermal conductivity and the surface temperature measurements were found suitable to differentiate between materials in the bond region, i.e., adhesive, cell walls and embedding epoxy. Of the two SThM modes available, the surface temperature mode provided images with superior optical contrast. The results clearly demonstrate that the polyurethane adhesive did not cause changes of thermal properties in wood cell walls with adhesive contact. By contrast, cell walls adjacent to a phenol-resorcinol-formaldehyde adhesive showed distinctly changed thermal properties, which is attributed to the presence of adhesive in the wood cell wall.

Flexible graphene composites with high thermal conductivity as efficient heat sinks in high-power LEDs

2018 ◽  
Vol 52 (2) ◽  
pp. 025103 ◽  
Author(s):  
J Oliva ◽  
A I Mtz-Enriquez ◽  
A I Oliva ◽  
R Ochoa-Valiente ◽  
C R Garcia ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Power ◽  
Heat Sinks ◽  
High Thermal Conductivity

A High Thermoelectric Performance ZT in p-Type LaSe2 Crystal

2021 ◽  
Vol 871 ◽  
pp. 203-207
Author(s):  
Jian Liu
Keyword(s):  
Thermal Conductivity ◽  
Power Factor ◽  
High Power ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Phonon Transport ◽  
Thermoelectric Performance ◽  
Boltzmann Transport ◽  
High Power Factor ◽  
P Type

In this work, we use first principles DFT calculations, anharmonic phonon scatter theory and Boltzmann transport method, to predict a comprehensive study on the thermoelectric properties as electronic and phonon transport of layered LaSe2 crystal. The flat-and-dispersive type band structure of LaSe2 crystal offers a high power factor. In the other hand, low lattice thermal conductivity is revealed in LaSe2 semiconductor, combined with its high power factor, the LaSe2 crystal is considered a promising thermoelectric material. It is demonstrated that p-type LaSe2 could be optimized to exhibit outstanding thermoelectric performance with a maximum ZT value of 1.41 at 1100K. Explored by density functional theory calculations, the high ZT value is due to its high Seebeck coefficient S, high electrical conductivity, and low lattice thermal conductivity .

Development of High Thermally Conductive Die Attach for TIM Applications

2019 ◽  
Vol 2019 (1) ◽  
pp. 000312-000315
Author(s):  
Maciej Patelka ◽  
Sho Ikeda ◽  
Koji Sasaki ◽  
Hiroki Myodo ◽  
Nortisuka Mizumura
Keyword(s):  
Thermal Conductivity ◽  
High Power ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Power Semiconductor ◽  
Die Attach ◽  
Industry Standards ◽  
Thermally Conductive ◽  
Low Modulus ◽  
Thermal Grease

Abstract High power semiconductor applications require a Thermal Interface Die Attach Material with high thermal conductivity to efficiently release the heat generated from these devices. Current Thermal Interface Material solutions such as thermal grease, thermal pads and silicones have been industry standards, however may fall short in performance for high temperature or high-power applications. This presentation will focus on development of a cutting-edge Die Attach Solution for Thermal Interface Management, focusing on Fusion Type epoxy-based Ag adhesive with an extremally low Storage Modulus and the Thermal Conductivity reaching up to 30W/mK, and also Very Low Modulus, Low-Temperature Pressureless Sintered Silver Die Attach with the Thermal Conductivity of 70W/mK.

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