Donor neutralization in GaAs(Si) by atomic hydrogen

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Abstract
Hydrogen plasma exposure of n-type GaAs(Si) at 250 °C results in a decrease of the free-carrier concentration by several orders of magnitude. This neutralization effect has been demonstrated in silicon-doped layers grown by molecular beam epitaxy or formed by annealed implants as well as in bulk material. The same effect is produced electrochemically (H3PO4 electrolyte), whereas helium plasma exposure has no effect, thus confirming the role of hydrogen insertion. The hydrogen penetration depth into GaAs(Si) is inversely dependent on the Si concentration. Recovery of the electrical activity follows first order dissociation kinetics with a dissociation energy of 2.1 eV. Complete restoration of free-carrier concentration occurs by heating at 420 °C for less than 3 min. Extrapolated to low temperatures, these results imply many years of stability at 150 °C or below.