Multilayered Thin-Film Materials for Phase-Change Erasable Storage

MRS Bulletin ◽  
1990 ◽  
Vol 15 (4) ◽  
pp. 40-45 ◽  
Author(s):  
Matthew Libera ◽  
Martin Chen
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Active Layer ◽  
Phase Change Materials ◽  
Optical Recording ◽  
Heat Sinks ◽  
Transmission Electron Micrograph ◽  
Irreversible Damage ◽  
Cross Sectional ◽  
Dielectric Layers

Phase-change erasable optical recording uses a focused laser beam as a heat source to reversibly switch a micron-sized area in a thin film between the amorphous and crystalline states. A bit of information is stored as an amorphous spot in a crystalline background, and the state of the bit is determined by the differing optical properties of the amorphous and crystalline phases. This concept was first demonstrated in 1971 and then, after about a decade of exploratory work, the field accelerated throughout the 1980s at several research laboratories. Currently the subject of number of reviews, the field of phase-change materials promises to broaden and intensify in the 1990s.The active layer, where the storage occurs, is typically a tellurium-based alloy with a variety of solute species. Early work studied the recording properties of single-layered films, but it has been clearly shown that multilayered films, where the active layer is sandwiched between two or more dielectric layers, have superior recording properties and resistance to irreversible damage caused by laser heating. The dielectric layers (typically SiO2, Si3N4, or ZnS) provide barriers to active-layer oxidation and contamination, help prevent the hole formation associated with ablative write-once storage methods, and act as crucibles and heat sinks which contain the molten spot and influence its cooling properties, respectively. A typical multilayer structure is shown in the cross-sectional transmission electron micrograph of Figure 1.

Studies on Optimum Distribution of Fins in Heat Sinks Filled With Phase Change Materials

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
S. K. Saha ◽  
K. Srinivasan ◽  
P. Dutta
Keyword(s):  
Phase Change ◽  
Thermal Management ◽  
Phase Change Materials ◽  
Volume Fraction ◽  
Heat Sinks ◽  
Electronic Systems ◽  
Optimum Distribution ◽  
Cross Sectional ◽  
Change Material ◽  
Small Cross Sectional Area

This paper deals with phase change material (PCM), used in conjunction with thermal conductivity enhancer (TCE), as a means of thermal management of electronic systems. Eicosane is used as PCM, while aluminium pin or plate fins are used as TCE. The test section considered in all cases is a 42×42mm2 base with a TCE height of 25mm. An electrical heater at the heat sink base is used to simulate the heat generation in electronic chips. Various volumetric fractions of TCE in the conglomerate of PCM and TCE are considered. The case with 8% TCE volume fraction was found to have the best thermal performance. With this volume fraction of TCE, the effects of fin dimension and fin shape are also investigated. It is found that a large number of small cross-sectional area fins is preferable. A numerical model is also developed to enable an interpretation of experimental results.

scholarly journals Cross-Sectional Observation of Ge-Sb-Te Amorphous Thin Film for Phase Change Optical Recording

Materia Japan ◽  
2003 ◽  
Vol 42 (12) ◽  
pp. 889-889
Author(s):  
Muneyuki Naito ◽  
Manabu Ishimaru ◽  
Yoshihiko Hirotsu ◽  
Masaki Takashima
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Optical Recording ◽  
Cross Sectional ◽  
Amorphous Thin Film

The effect of an aluminum heat-sink layer on the laser-induced amorphization of SiOx/TeGeSn/SiOx phase-change recording films

1989 ◽  
Vol 47 ◽  
pp. 574-575
Author(s):  
Matthew R. Libera ◽  
Martin Chen
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Heat Sink ◽  
Multilayer Film ◽  
Glassy Phase ◽  
Film Structure ◽  
Glass Forming ◽  
Active Storage ◽  
Dielectric Layers ◽  
Amorphous States

Phase-change erasable optical storage is based on the ability to switch a micron-sized region of a thin film between the crystalline and amorphous states using a diffraction-limited laser as a heat source. A bit of information can be represented as an amorphous spot on a crystalline background, and the two states can be optically identified by their different reflectivities. In a typical multilayer thin-film structure the active (storage) layer is sandwiched between one or more dielectric layers. The dielectric layers provide physical containment and act as a heat sink. A viable phase-change medium must be able to quench to the glassy phase after melting, and this requires proper tailoring of the thermal properties of the multilayer film. The present research studies one particular multilayer structure and shows the effect of an additional aluminum layer on the glass-forming ability.

Electron Microscopy Study on Amorphous Ge-Sb-Te Thin Film for Phase Change Optical Recording

2003 ◽  
Vol 42 (Part 2, No. 10A) ◽  
pp. L1158-L1160 ◽  
Author(s):  
Muneyuki Naito ◽  
Manabu Ishimaru ◽  
Yoshihiko Hirotsu ◽  
Masaki Takashima
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Phase Change ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Optical Recording

Transistors with a Profiled Active Layer Made by Hot-Wire Cvd

1998 ◽  
Vol 507 ◽  
Author(s):  
H. Meiling ◽  
A.M. Brockhoff ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Thin Film ◽  
Active Layer ◽  
Hot Wire ◽  
Semiconductor Interface ◽  
Cross Sectional ◽  
Silicon Matrix ◽  
Bias Stress ◽  
Silicon Devices ◽  
Transmission Electron ◽  
Conducting Research

ABSTRACTIn order to obtain stable thin-film silicon devices we are conducting research on the implementation of hot-wire CVD amorphous and polycrystalline silicon in thin-film transistors, TFFs. We present results on TFTs with a profiled active layer (deposited at ≥9 Å/s), and correlate the electrical properties with the structure of the silicon matrix at the insulator/semiconductor interface, as determined with cross-sectional transmission electron microscopy. Devices prepared with an appropriate H2 dilution of SiH4 show cone-shaped crystalline inclusions. These crystals start at the interface in some cases, and in others exhibit an 80nm incubation layer prior to nucleation. The crystals in the TFTs with the incubation layer are not cone-shaped, but are rounded off. The hot-wire CVD deposited devices exhibit a high fieldeffect mobility up to 1.5 cm2V−1s−l. Also, these devices have superior stability upon continuous gate bias stress, as compared to conventional glow-discharge α-Si:H TFTs. We ascribe this to a combination of enhanced structural order of the silicon and a low hydrogen content.

Design of a Microscale Breather for Two-Phase Thermal Management Devices

2008 ◽  
Author(s):  
B. R. Alexander ◽  
E. N. Wang
Keyword(s):  
Phase Change ◽  
Removal Rate ◽  
Heat Removal ◽  
Design Guidelines ◽  
Heat Sinks ◽  
Two Phase ◽  
Cross Sectional ◽  
Optical Visualization ◽  
Gas Removal ◽  
Microchannel Heat Sinks

Two-phase microchannels promise an efficient method to dissipate heat from high performance electronic systems by utilizing the latent heat of vaporization during the phase-change process. However, phase-change in microchannel heat sinks leads to challenges that are not present in macroscale systems due to the increasing importance of surface tension and viscous forces. In particular, flow instabilities often occur during the boiling process, which lead to liquid dry-out in the microchannels and severely limits the heat removal capabilities of the system. We propose a microscale breather device consisting of an array of hydrophobic breather ports which allow vapor bubbles to escape from the microchannels to improve flow stability. In this study, we use the combination of microfabricated structures and surface chemistry to separate vapor from the liquid flow. We designed test devices that allow for cross-sectional optical visualization to better understand the governing parameters of a breather design with high vapor removal efficiencies and minimal liquid leakage. We examined breather devices with average liquid velocities ranging from 0.5 cm/s to 4 cm/s and breather vacuum levels between 1 kPa and 9 kPa on the maximum gas removal rate through the breather. We demonstrated successful breather performance. In addition, a model was developed that offers design guidelines for future integrated breathers in microchannel heat sinks. The breathers also have significant promise for other microscale systems, such as micro-fuel cells, where liquid-vapor separation can significantly enhance system performance.

scholarly journals Computational Study of Heat Transfer inside Different PCMs Enhanced by Al2O3 Nanoparticles in a Copper Heat Sink at High Heat Loads

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 284 ◽  
Author(s):  
Nadezhda S. Bondareva ◽  
Nikita S. Gibanov ◽  
Mikhail A. Sheremet
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Computational Study ◽  
Conjugate Problem ◽  
High Heat ◽  
Solid Particles ◽  
Heat Sinks ◽  
Al2o3 Nanoparticles ◽  
Electronic Elements ◽  
The Impact

The cooling of electronic elements is one of the most important problems in the development of architecture in electronic technology. One promising developing cooling method is heat sinks based on the phase change materials (PCMs) enhanced by nano-sized solid particles. In this paper, the influence of the PCM’s physical properties and the concentration of nanoparticles on heat and mass transfer inside a closed radiator with fins, in the presence of a source of constant volumetric heat generation, is analyzed. The conjugate problem of nano-enhanced phase change materials (NePCMs) melting is considered, taking into account natural convection in the melt under the impact of the external convective cooling. A two-dimensional problem is formulated in the non-primitive variables, such as stream function and vorticity. A single-phase nano-liquid model is employed to describe the transport within NePCMs.

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