Band-gap renormalization in highly excited GaN

We have studied the band-gap renormalization in highly excited GaN thin films by means of photoluminescence (PL) spectral measurements from 6 to 300 K. The renormalized band-gap energy is determined from the low-energy edge of the broad PL band due to the high-density electron and hole (e–h) plasmas. The reduction of the band-gap energy depends on the density of e–h plasmas, but is independent of temperature. The renormalized band-gap energy is calculated using two theoretical models. Our results suggest that the e–h pair correlation plays an essential role in highly excited GaN.