Ion damage effects from negative deflector plate voltages during the plasma-assisted molecular-beam epitaxy growth of dilute nitrides

Abstract

We studied the effects of ion damage on the optical properties of dilute nitrides grown by plasma-assisted molecular-beam epitaxy. A dual-grid retarding field ion energy analyzer was used to measure the ion flux and ion energy distribution at the substrate position from an Applied-EPI UniBuilb™ rf plasma cell. These changes were measured as the negative deflector plate voltage varied from 0 to −800V. The largest ion flux resulted with a −100V setting, while the greatest ion energies occurred with −200V. Deflector plate voltages more negative than −300V resulted in a significant reduction in both the ion flux and ion energy. The damage caused by these ions was determined by measuring the pre- and postanneal photoluminescence properties of Ga0.8In0.2N0.01As0.99 quantum wells. Comparable optical properties were possible with various combinations of ion fluxes and ion energies, which demonstrate how the ion flux and ion energy each impart an individual effect on the sample’s optical properties. An awareness of these effects is crucial because the optical properties of dilute nitrides grown with an improper deflector plate voltage setting can lead to a greater degree of ion damage to the sample.