Growth of diamond film using CVD

This example computes the growth rate of a diamond film according to a simplified version of a particular published growth mechanism (see diamond.yaml for details). Only the surface coverage equations are solved here; the gas composition is fixed. (For an example of coupled gas-phase and surface, see catalytic_combustion.py.) Atomic hydrogen plays an important role in diamond CVD, and this example computes the growth rate and surface coverages as a function of [H] at the surface for fixed temperature and [CH3].

Requires: cantera >= 2.6.0, pandas >= 0.25.0, matplotlib >= 2.0

Tags: Python surface chemistry kinetics

import csv
import matplotlib.pyplot as plt
import pandas as pd
import cantera as ct

Import the model for the diamond (100) surface and the adjacent bulk phases

d = ct.Interface("diamond.yaml", "diamond_100")
g = d.adjacent["gas"]
dbulk = d.adjacent["diamond"]

mw = dbulk.molecular_weights[0]

t = 1200.0
x = g.X
p = 20.0 * ct.one_atm / 760.0  # 20 Torr
g.TP = t, p

ih = g.species_index('H')

xh0 = x[ih]

Calculate growth rate as a function of H mole fraction in the gas

with open('diamond.csv', 'w', newline='') as f:
    writer = csv.writer(f)
    writer.writerow(['H mole Fraction', 'Growth Rate (microns/hour)'] +
                    d.species_names)

    iC = d.kinetics_species_index('C(d)')

    for n in range(20):
        x[ih] /= 1.4
        g.TPX = t, p, x
        d.advance_coverages(10.0)  # integrate the coverages to steady state
        carbon_dot = d.net_production_rates[iC]
        mdot = mw * carbon_dot
        rate = mdot / dbulk.density
        writer.writerow([x[ih], rate * 1.0e6 * 3600.0] + list(d.coverages))

    print('H concentration, growth rate, and surface coverages '
          'written to file diamond.csv')

H concentration, growth rate, and surface coverages written to file diamond.csv

Plot the results

data = pd.read_csv('diamond.csv')

data.plot(x="H mole Fraction", y="Growth Rate (microns/hour)", legend=False)
plt.xlabel('H Mole Fraction')
plt.ylabel('Growth Rate (microns/hr)')
plt.show()

names = [name for name in data.columns if not name.startswith(('H mole', 'Growth'))]
data.plot(x='H mole Fraction', y=names, legend=True)
plt.xlabel('H Mole Fraction')
plt.ylabel('Coverage')
plt.show()