Effect of grown-in biaxial strain on deep level defects in Si1-yCy/Si epitaxial heterostructures

We report the first study of traps in strained Si1-yCy random alloys grown on Si [100] substrates using chemical vapor deposition. Deep level transien t spectroscopy (DLTS) measurements of n-type Schottky diodes fabricated on Si/Si1-yCy/Si heterostructures (y < 0.02) were used to study the impact of carbon and grown-in strain on the formation of deep levels. The observed de ep level activation energies were found to vary with carbon fraction, and r anged between 0.175 and 0.225 eV, measured with respect to the conduction b and. The systematic variation in the measured activation energies with carb on fraction suggests the splitting of a single deep level due to strain in the Si1-yCy alloy layer. The DLTS peaks exhibit anomalous broadening which increases with increasing carbon fraction and can be explained using an all oy broadening model. (C) 1999 Elsevier Science B.V. All rights reserved.