Thermal cleaning of air-exposed p-type InGaAs films and CBE regrowth of carbon-doped InGaAs layers for optical device applications

Abstract

We have studied thermal cleaning of air-exposed Zn-doped InGaAs films and regrowth of carbon-doped InGaAs layers in terms of carrier concentration profiles and residual oxides. As the cleaning temperature prior to CBE regrowth is increased, the residual oxides at the regrowth interface exponentially decrease, and the carrier concentration at the interface approaches the intentional doping level. Elevating the temperature to 575°C provides a “clean” interface, i.e., the carrier profiles are flat. SIMS reveals that the carbon atoms doped to 10 20 cm −3 in the CBE film do not diffuse to the adjacent Zn-doped MOCVD film at all. The thermal cleaning and regrowth procedure was applied to an air-exposed MOCVD film with laser structure for the purpose of nonalloy ohmic contact layer. 1.3 μm-wavelength buried-heterostructure laser diodes with cleaved facets have a large light output of more than 20 mW per facet.