DYNAMIC JAHN-TELLER EFFECT FOR A DOUBLE ACCEPTOR OR ACCEPTOR-BOUND EXCITON IN SEMICONDUCTORS - MECHANISM FOR AN INVERTED LEVEL ORDERING

The dynamic Jahn-Teller effect provides a simple mechanism for inverti ng the ordering of the J = 0, 2 levels of the two equivalent holes in a neutral double acceptor or an exciton bound at a neutral acceptor. W hereas Hund's rule places the J = 2 level below J = 0, Jahn-Teller cou pling to E and/or T2 vibrational modes tends to shift J = 0 below J = 2, while splitting J = 2 into its GAMMA3 and GAMMA5 components. Altern ative proposed explanations involving central-cell, Stark, and strain effects fail to introduce the attractive interaction needed to offset the hole's Coulomb repulsion.