Figures

Figure 1

Growth structure of the modulation doped quantum well sample.

Figure 2

Photoluminescence spectra of a modulation doped GaN/AlGaN QW with different excitation photon energies, as indicated by the arrows. The topmost spectrum was excited with 3.72 eV photons. The three middle peaks originate from emissions in the QW. The energetically lowest emission is from the GaN buffer layer, and the highest energy emission originates from the AlGaN barrier.

Figure 3

Schematic energy band model of the modulation doped GaN/AlGaN QW with a weak piezoelectric field across the well. Also shown are the confined states, and the suggested transitions involved are indicated by arrows. The Fermi energy is believed to lie close to the third electron subband in the QW. (The wavefunctions and energy positions of the confined states are from a calculation with a 165 keV/cm piezoelectric field across the QW.)

Figure 4

Temperature dependence of the PL spectra for the same GaN/AlGaN QW as in Figure 1. Spectral curves (starting from the top) are measured at 3, 10, 20, 30, 40 and 100 K, respectively.

Figure 5

Time resolved decay curves for the five different peaks shown in Figure 1. The curves are measured at (from the top) 3.54, 3.59, 3.62, 3.66, and 3.49 eV, respectively.

© 1999 The Materials Research Society