Spin polarized photoemission from molecular beam epitaxy-grown be-doped GaAs

Polarization and charge limit studies of strained GaAs photocathodes

“…Experimental evidence supports the idea that the (1 11B) surface in GaAs yields the highest polarization. [43] Moreover, Fig. 5.2 shows how experimental evidence also supports the idea that the (1 11B) surface yields the highest QE.…”

A polarized photoluminescence study of strained layer GaAs photocathodes

“…These neglected terms, along with some second order perturbation terms, are linear in k and cause a shift of the valence band maxima from the T point when appropriately accounted for. [21] The spin orbit interaction terms included in the interaction matrix are of the form 12) <Y|(t)|#J 0 |£tU)) = +(-)iA , (2.13) [2][3][4][5][6][7][8][9][10][11][12][13][14] This interaction requires the eigenfunctions to be states of J and rrij. Kane obtained solutions for the complete interaction, Hk.…”

“…First, the theoretical 50% polarization limit has been approached in practice by designing cathodes with sufficiently thin active layers. [3] [4] With a thin active layer, the average electron escape time is presumably much shorter than any spin relaxation times associated with the material and the effect of spin depolarization within the semiconductor is thus minimized. Secondly, the cathode may be used either in a CW mode or pulsed, with pulse lengths as short as 40 psec, [5] by appropriate choice of pump laser.…”

“…Next, 2 /im of In a;o Ga(i_ a;o )P was grown, followed by the 100 nm strained GaAs layer. All layers were Be doped at 4-6xl0 18 /cm 3 . This sample did not become available until most data had been collected for the other samples.…”

Polarization studies of strained GaAs photocathodes at the SLAC Gun Test Laboratory

“…A polarization dependence on crystal orientation has been observed before [12]. The crystal orientation and surface composition determine the density of surface states and the amount of band-bending [13].…”