Hydrostatic-pressure dependence of bound excitons in GaP

We report for the first time an investigation of the low-temperature hydrostatic-pressure dependence of bound excitons in GaP. We have used a hydrostatic-pressure cell equipped with an optical window and filled with a transparent pressure-transmitting medium. Working with a sample temperature of about 5 K, we could reach a maximum pressure of 8 kbar and examined various recombination lines. This work reports the change in radiative recombination energy of (i) excitons bound to a single neutral donor (D0X complex), (ii) excitons bound to a single isoelectronic impurity (NX complex), and (iii) excitons bound to a pair of isoelectronic defects (NNX complexes). We find non-linear behaviors associated with the binding of an exciton around an isoelectronic trap. This is discussed in the light of existing model calculations. © 1984 The American Physical Society.