Stress effects on excitons bound to neutral acceptors in InP

We present stress-dependent photoluminescence measurements on excitons bound to neutral acceptors in InP. We analyze the experimental results in two theoretical schemes: a $j-j$ coupling scheme and a crystal-field scheme. We find that the triplet structure of the ($A^{0}X$) complex results from hole-hole coupling in the cubic crystal field. We show that the three bound-exciton states correspond to ${\Gamma }_8,{\Gamma }_{7,8}, \mathrm{and} {\Gamma }_6$ in order of increasing energies, the electron-hole exchange energy being found to be vanishingly small.