Growth-induced temperature changes during transition metal nitride epitaxy on transparent SiC substrates

Noncontact band edge thermometry based on diffuse reflectance was used to monitor and control the substrate temperature rise during the MBE growth of niobium nitride transition metal nitrides on transparent, wide-bandgap silicon carbide substrates. Temperature transients as large as 135 degrees C are induced by changing the main substrate shutter state. The growth of niobium nitride films as thin as similar to 5nm leads to temperature increases as large as 240 degrees C. In addition, a temperature decrease during the growth of ultrawide-bandgap AlN films on niobium nitride was observed and characterized. The causes of the observed temperature excursions are explained by considering the Stefan-Boltzmann law, and ways to better control the substrate temperature are discussed.