Hydrogen patterning of Ga1-xMnxAs for planar spintronics

We demonstrate two patterning techniques based on hydrogen passivation of Ga1-xMnxAs to produce isolated ferromagnetically active regions embedded uniformly in a paramagnetic, insulating host. The first method consists of selective hydrogenation of Ga1-xMnxAs by lithographic masking. Magnetotransport measurements of Hall-bars made in this manner display the characteristic properties of the hole-mediated ferromagnetic phase, which result from good pattern isolation. Arrays of Ga1-xMnxAs dots as small as 250 nm across have been realized by this process. The second process consists of blanket hydrogenation of Ga1-xMnxAs followed by local reactivation using confined low-power pulsed-laser annealing. Conductance imaging reveals local electrical reactivation of micrometer-sized regions that accompanies the restoration of ferromagnetism. The spatial resolution achievable with this method can potentially reach <100 nm by employing near-field laser processing. The high spatial resolution attainable by hydrogenation patterning enables the development of systems with novel functionalities such as lateral spin-injection as well as the exploration of magnetization dynamics in individual and coupled structures made from this novel class of semiconductors.Comment: ICDS-24, July 2007. 8 pages with 4 figure

Neutralization of manganese by hydrogen in GaAs

Ga1−xMnxAs samples, with x in the percent range, grown by molecular beam epitaxy at low temperature have been hydrogenated or deuterated by exposure to plasmas. At liquid helium temperature, the samples show local vibrational modes (LVMs) at about 2141 and 1546 cm−1 in hydrogenated and deuterated layers, respectively. These LVMs evidence the formation of electrically inactive complexes involving manganese and hydrogen. Hydrogen sits most likely in bond center location between manganese and arsenic atoms; it is mainly bonded with the arsenic atom. It is argued that the manganese–hydrogen complex is the unidentified acceptor–hydrogen complex discussed in literature