Preparation of Discontinuous Layers

An alternative approach for preparation of nanostructured composites is to use sequential vapor deposition of semiconductors (metals) and insulating (semiconductor) materials. The Stranski-Krastanow self-organized epitaxial growth of III-V [183] and, more recently, II-VI semiconductor nanocrystals [184, 185] in strained systems has attracted much attention. This mechanism takes place on the smooth surface of a crystalline material, but it can explain the nano-crystal growth observed on a rough surface [180, 185-189]. This nonepitaxial self-organized nanocluster formation has

Table 1. Silicon and germanium-based regular multilayers.

Multilayer

Preparation technique

Crystallization

a-Si:H/a-SiN, :H

plasma enhanced CVD [139]; radio frequency

furnace annealing [112]; rapid thermal annealing [139];

plasma enhanced CVD [126-130];

laser beam crystallization [126-130];

a-Si:H/Si1-ICI

glow discharge

furnace annealing [112], interdiffusion

a-Si:H/a-Ge:H

glow discharge

furnace annealing [62, 116], interdiffusion

a-Si/SiO2

plasma enhanced CVD [61, 63, 64, 67]; rf magnetron

furnace annealing [63, 64, 90, 91, 124]; rapid thermal

sputtering [63, 118, 122]; low pressure CVD [90, 91];

annealing [125];

a-Si:H/SiO2

low pressure CVD, layer-by-layer plasma oxidation

rapid thermal annealing plus furnace annealing [56]

a-Si/SiO2

electron beam evaporation, in-situ plasma oxidation;

furnace annealing [48-50, 61, 67]

magnetron sputtering [70]

a-Si/SiO2

molecular beam epitaxy [45-47]

nc-Si/SiO2

rapid thermal CVD

[57]

nc-Si/a-Si

glow discharge

intermediate annealing in a hydrogen plasma [147]

a-Si:H/a-Ge:H

glow discharge

furnace annealing [62, 116], interdiffusion

a-Ge/SiO,

furnace annealing, interdiffusion [124]

a-Ge:H/a-SiN, :H

rf glow discharge CVD

furnace annealing [103]

a-Ge:H/a-GeN,

rf reactive sputtering

furnace annealing [66, 101, 114]

a-Ge/a-GeN,

rf reactive sputtering

furnace annealing [66, 101, 114]

a-Ge/a-Se

furnace annealing [74]

a-Ge/a-C

magnetron sputtering [14]

a-Ge,Cy :H/a-Ge, Cy :H

continuous plasma enhanced CVD [65]

SiO, /GeOy

reactive sputtering of Si and Ge

furnace annealing [148]

been used for fabrication of nanoparticle layers buried in thin film matrices. It occurs on the rough surface of amorphous, thin films deposited by means of physical evaporation, sputtering, or glow-discharge techniques.

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