LASER RECOMBINATION TRANSITION IN p-TYPE GaAs

Abstract

Data are presented (77°K) showing that laser transitions to either the valence band edge or to the acceptor, or both, are possible in a specific impurity concentration range (2 × 1017−1018/cm3) in GaAs:Zn and GaAs:Cd. These data are observed on a low-loss crystal structure that is pumped uniformly.

Fixed-point actions in 1-loop perturbation theory

“…We recapitulate and extend the arguments on the mass gap [10,11] in Section 2. We use this occasion to clarify some issues on off-mass shell versus on-mass shell improvement and on the relation between Symanzik improvement and the FP action.…”

“…Consider the finite-volume mass gap m(L) defined on a strip 0 ≤ x ≤ L, −∞ < t < +∞, with periodic boundary condition in x. In perturbation theory this has an expansion [14,15,10]…”

“…We show now that the tree level on-shell Symanzik conditions cancel the O(a 2 ) 1-loop artifacts in the mass gap m(L). The 1-loop contribution A 1 (L) to Lm(L) can be written as [10]…”

“…Here the terms r 1 , r 2 come from the quadratic couplings ρ in eq. (2.3) while s 1 and s 2 from the quartic couplings c. The corresponding expressions [10] could be written in a common form:…”

“…The mass gap is, however, a special quantity: any action gives cut-off independent results for m(L)L on the tree level. It has been conjectured and illustrated through examples recently [10,11] that in this case tree level improvement will become effective on the 1-loop level cancelling the cut-off effects there. The mass gap therefore is not appropriate to test the issue at hand.…”