Deposition of Diamond Film on Aluminum Nitride Ceramics and the Study of Their Thermal Conductance

Diamond films(DF)have been deposited on AlN ceramic substrates by hot filament chemical vapour deposition method.The diamond nucleation on AlN ceramics has been investigated.A nucleation density more than 10^(8) cm^(-2) was obtained on this kind of insulating polycrystalline substrate under common deposition conditions.The thermal conductance of the DF/AlN compound materials has been studied by photothermal deflection technique.The thermal diffusivity of the DF/AlN is higher than that of the AlN ceramics,and will increase as the diamond films grow thicker.

Initial Growth of Thin Films with Low Nucleus Density and Linear Lateral Growth Rate on a Substrate Surface

Based on corrected rate equations,the kinetics is revealed for initial growth of thin films with low nucleus density and linear lateral growth rate on a substrate surface.In this case,the mobility and coalescence terms in rate equations are neglected,and the coverage term takes a dominant role.All the calculated results are in agreement with experimental data.These results introduce a new scaling in the case of dominant coverage,which is different from the those in the case of coalescence or mobility in a dominant role.

Investigation of Diamond Films Deposited on LaAlO_(3) Single Crystal Substrates by Hot Filament Chemical Vapor Deposition

Diamond nucleation and growth on a LaAlO_(3) single crystal substrate,whose lattice mismatch with diamond is only 7.2%at high temperature,were investigated for the first time.As an insulating substrate,a nucleation density of more than 108 cm_(-2) was achieved on ultrasonically cleaned wafers.A free-standing diamond film was obtained for 65 h growth and characterized by scanning electron microscopy,Raman and x-ray photoelectron spectroscopy.The results show that LaAIO3 single crystal is a good candidate substrate for diamond film growth.

Interface Electronic Structure of Ge/ZnSe(111)

Using linear muffin-tin orbitals method with atomic sphere approximation,the interface electronic structure of Ge/ZnSe(111)has been studied.The density of states,local density of states as well as local partial density of states are presented.The interface electronic structure and the interaction characteristics between interface atoms are analyzed.The results show a significant effect of the interface atomic arrangement on the electronic structures.

Effect of Growth Temperature on the Band Lineup of Ge/CdTe(111) Polar Interfaces

By using synchrotron radiation photoelectron spectroscopy,the band lineup of Ge/CdTe(111)interfaces grown at different temperatures have been measured.Experimental studies show that the valence band offset of Ge/CdTe(111)interface grown at room temperature is 0.88±0.1 eV,which agrees well with previously reported value.While as for the interface grown at 280℃,an obvious reduction of valence band offsets is observed and attributed to sthe effect of different interface dipole.

Thermal Conductivity of Diamond-Based Silicon-on-Insulator Structures

Diamond films of various thickness(1-300μm)were deposited on single-crystal Si active(300μm)by a microwave plasma chemical vapor deposition method using gaseous mixtures of methane and hydrogen.After thinning of the Si layer by machine and ion-beam polishing a diamond-based silicon-on-insulator structure with final Si layer thickness of about 1μm is formed.Thermal conductivity of this structure material with various thicknesses of diamond and Si layer was measured.Compared with bulk silicon,the thermal conductivity of the siliconon-diamond structure with 300μm diamond and 1μm silicon increases by 850%.

Emission Spectroscopy for Hot Filament Diamond Growth Process with Positive Substrate Biasing

Optical emission spectrum has been successfully measured on a hot filament diamond growth process witb substrate biasing.The emission lines of atomic hydrogen , H_(2),CH and CH^(+) were observed.EfFects of methane concentration on the emission intensity of observed lines were systematically studied.The experimental results suggest that atomic hydrogen and CH^(+) radicals play an important role in diamond growth,while CH radical facilitates the formation of amorphous carbon.