Bound excitonic region

Figure 3.10 shows the bound exciton region of the 10 K PL spectrum for the melt-grown bulk sample (from Cermet, Inc.) characterized by Teke et al. [50]. The prominent lines are positioned at 3.3564 (Ig), 3.3598 Is), 3.3605 (,), 3.3618 (Is), 3.3650 I4), 3.3664 (I3), and 3.3724 (Iq) eV. The 3.3605 eVline is the most intense and has a full-width at half-maximum (FWHM) of about 0.7 meV, indicating the high quality of the sample. Several small peaks and shoulders can also be seen between these prominent lines. Different assignments for these emission peaks are present in... 

Figure3.10 Bound excitonic region of the 10 K PL spectrum for a forming gas-annealed ZnO substrate. (After Ref [50])...

Fig. 17 Photoluminescence spectra covering the no-phonon and TA phonon-replica energy regions taken at 4.2 K. The spectra show the bound exciton luminescence of samples implanted with B, In, and T1 before (a, c, e) and after (b, d, f) treatment in atomic H. Bound exciton luminescence due to the implanted impurities has been shaded in to distinguish it from the substrate luminescence. From Thewalt et al. (1985).

Low temperature photoluminescence (PL) spectra of all samples with SiN nanonetwork exhibited similar features around the band edge which are dominated by exciton peaks, but with steady improvement with increasing SiN coverage. Figure 6.11 shows the excitonic region of PL signal measured at 15 K for sample with 5 and 6 min SiN compared with control sample. The spectra contain peaks at 3.485, 3.494 and 3.505 eV which correspond to FXa, FXb, and FXa excited state transitions, respectively [10]. The main donor-bound exciton D°Xa emission is seen at 3.479 eV. The FWFLM values of the FX a, FX b and D°X a peaks... 

The intensity of the bound-exciton peaks, relative to that of the free-exciton features, gives an indication of the uncompensated boron concentration in the region of the diamond examined. For the diamond shown in Fig. 6b this is about 5 X 10 cm as determined from Hall effect measurements (31). A very weak peak D, due to the accidental presence of a small concentration of boron (estimated as 3 X 10 cm ), is also evident in the low-temperature spectrum in Fig. 5. 

Another characteristic of the neutral donor-bound exciton transition is the TES transition in the spectral region of 3.32-3.34 eV. These transitions involve radiative recombination of an exciton bound to a neutral donor, leaving the donor in the excited state (2s, 2p states), thereby leading to a transition energy that is less than the DBE energy by an amount equal to the energy difference between the first excited (2s, 2p)... 

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