OPTICAL-PROPERTIES OF SI-DOPED GAN

The optical properties of n-type GaN are investigated for Si doping co ncentrations ranging from 5 x 10(16) to 7 x 10(18) cm(-3). The photolu minescence linewidth of the near-band gap optical transition increases from 47 to 78 meV as the doping concentration is increased. The broad ening is modeled in terms of potential fluctuations caused by the rand om distribution of donor impurities. Good agreement is found between e xperimental and theoretical results. The intensity of the near-band-ga p transition increases monotonically as the doping concentration is in creased indicating that nonradiative transitions dominate at a low dop ing density. The comparison of absorption, luminescence, reflectance, and photoreflectance measurements reveals the absence of a Stokes shif t at room temperature demonstrating the intrinsic nature of the near-b and edge transition. (C) 1997 American Institute of Physics.