Structural and phase composition features of carbon

films grown by DC PECVD process

A.A. Zolotukhin, A.P. Volkov, A.O. Ustinov, A.N. Obraztsov,

Physics Department of Moscow State University

Introduction In this work we present the results of in-situ and ex-situ Raman

spectroscopic examination of CVD diamond films deposited in a DC discharge plasma. Despite a considerable interest in the CVD technology and the wide use of Raman spectroscopy for the characterisation of diamond CVD films, only a few experiments were described in the literature that were devoted to the Raman in-situ diagnostics of diamond films. The in-situ Raman measurements can be used for determining the temperature of films, because conventional optical pyrometry is hindered by intense emission from the plasma region. Position of Raman lines may also change as a result of the mechanical stresses developed in the material application of an external load.

Scheme of Experimental Setup

High voltage DCpower supply

Cu-vapor laser

H2CH4

Rotary pumpMass-flowcontrollers

Monochromator

Stainless steelwater-cooled

reactor

Optical windowsTungsten

ring cathode

Substrate

Scheme of a setup for in-situ monitoring of the Raman spectra.

COMPOSITION AND SURFACE MORPHOLOGY STUDIES

800 1000 1200 1400 1600 1800

Ram

an In

tens

ity, [

arb.

un.]

Raman Shift, [cm-1]

RS of typical polycrystalline diamond

SEM Image of typical diamond polycrystalline CVD film

1000 1200 1400 1600 1800

R

aman

Inte

nsity

, [ar

b.un

.]

Raman Shift, [cm-1]

RS of nanocrystalline diamond

AFM image of typical diamond nanocrystalline CVD film

RS of CVD graphite-like film material

SEM image of typical graphite-like CVD film

HRTEM of a fragment of carbon nanotubes in the CVD film

TEM image of typical graphite-like CVD film

1000 1200 1400 1600 1800

3R

am

an Inte

nsity, [a

rb.u

n.]

2

1

Raman Shift, [cm-1]

Raman spectra measured in situ in the course of carbon deposition: (1) amorphous carbon film; (2) diamond film composed of nanocrystals;

(3) diamond film composed of a well crystallites.

In-situ Raman spectroscopy of CVD diamond films

1200 1300 1400 1500

3

2

1

Ra

ma

n I

nte

nsity,

[arb

.un

.]

Raman Shift, [cm-1]

Raman spectra of diamond films measured in-situ at various time instants after the begining of deposition: (1) 15; (2) 30; (3) 45 min;

1100 1200 1300 1400 1500

3

2

1

Ram

an In

tens

ity, [

arb.

un.]

Raman Shift, [cm-1]

0 200 400 600 800 1000 12001300

1310

1320

1330

Ra

ma

n S

hift

, [c

m-1]

Temperature, [oC]

Raman spectra of diamond films measured in-situ at various substrate

temperatures: (1)25; (2)1000; (3) 1200°C.

Position of the “diamond” Raman line (1332cm-1) versus the film

temperature: (points) this experiment; (dashed line) the plot measured on

a diamond single crystal

C. Johnson, A. Crosley, P.R. Chalker, et al., Diamond and

Related Mat., 1 (1992) 450.

the experiment

1200 1300 1400 1500

5432

1

Ram

an In

tens

ity, [

arb.

un.]

Raman Shift, [cm-1]-100 0 100 200 300

1300

1320

1340

1360

1380

1400

1420

543

21

Ra

ma

n S

hift

, [c

m-1]

Pressure, [kbar]

Raman spectra of a diamond film measured in-situ at various time instants after the begining of its etching in a hydrogen plasma:

(1) 15; (2)30; (3)45; (4)60; (5)90 min.

Position of the “diamond” Raman line (1332 cm-1) versus the pressure:(dashed line) the plot measured

on a diamond single crystal; (points) polycrystalline diamond film measured in-situ

in the course of etching in a hydrogen plasma.

M. Hanfland and K.Syassen., J. Appl. Phys., 1985, vol.57,

p. 2752.

the experiment

Conclusions

The CVD method was used for fabrication of different thin film carbon materials. Their structural, morphology, phase composition properties were studied by a number of experimental methods including Raman, SEM, STM, AFM, TEM, HRTEM.

The original in-situ Raman spectrometer was elaborated and a set of experiments performed to study specificity of the diamond CVD growth in plasma activated by DC discharge.