Properties and use of cycled grown OMVPE GaAs:Zn, GaAs:Se, and GaAs:Si layers for high-conductance GaAs tunnel junctions

Abstract

Heavily doped GaAs layers for high conductance GaAs tunnel junctions have been grown by atmospheric pressure organometallic vapor phase epitaxy (OMVPE) using Zn as the dopant for thep + regions and either Se or Si as the dopant for then + regions. At a growth temperature of 700° C using a “cycled” growth technique for the Zn-dopedp ++-GaAs layer, both the conductance and the peak current density of the tunnel diode has been increased by a factor of ∼65 compared to a tunnel junction with a continuously grown Zn-doped p+-GaAs. The conductance of the tunnel junction, which is maximized at a growth temperature of 650° C using cycled growth, is comparable to the best reported values for tunnel junctions grown by molecular beam epitaxy. Cycled growths forn + Se-doped regions are found to reduce the conductance of a tunnel junction by more than two orders of magnitude. However, cycled growth for the n+-GaAs regions with Si doping show no conductance degradation. A model based on incorporation sites of these dopants during OMVPE growth of GaAs is presented to account for the experimental observations.