Diffusivity of positively charged hydrogen in GaAs

The diffusivity of positively charged hydrogen (${\mathrm{H}}^{+}$) in GaAs has been directly determined from capacitance transient measurements. The hydrogen was released from donor-hydrogen complexes in the space charge layer of Schottky diodes on n-type GaAs by pulsed-laser injection of minority carriers. Capacitance-voltage measurements reveal the recovery of donor dopants after the injection, which demonstrates minority-carrier-enhanced dissociation of a donor-hydrogen complex in GaAs. Analysis of capacitance transients recorded during migration of ${\mathrm{H}}^{+}$ were analyzed to obtain diffusivities near room temperature; at 320 K the diffusivity is ∼1×${10}^{\mathrm{-}12}$ ${\mathrm{cm}}^2$/sec, within a factor of 2. An Arrhenius analysis of the migration time constant yields an activation energy for ${\mathrm{H}}^{+}$ diffusion of ∼0.66 eV.