Isotopic Homojunction Band Engineering from Diamond

Abstract

Confining Carriers in Diamond Charge carriers can be confined in thin layers created by quantum wells. These multilayer structures alternate nanoscale layers of materials with slightly different band-gap energies, such as AlGaAs and GaAs, and create a confining potential. Watanabe et al. (p. 1425 ) demonstrate quantum confinement of electrons by diamond multilayers that vary only in isotopic composition; the carbon-12 and carbon-13 layers differ in band-gap energy by ∼17 millielectron volts. Cathodoluminescence experiments performed at 80 kelvin showed that in alternating layers (as thin as 30 nanometers or as thick as 350 nanometers), emission comes from charge carriers recombining in the carbon-12 layer, which has a lower band gap. Carriers from the carbon-13 layer appear to transfer with little loss into carbon-12 layers.