Abstract
Opal consists of a three dimensional array of silica balls with diameter in the range 150-350 nm and acts as a 3-D grating. Within the microcrystals (a few hundred microns) of opal there is typically 5% variation in ball diameter arranged in a fcc structure. Using a specially modified MOCVD process InP can be grown within the voids between the touching silica balls. These interconnecting voids are approximately 1/5 and 2/5 the silica sphere diameter. Raman spectroscopy confirms the crystallinity of the InP for two samples loaded with 2.5 volume % of InP. The LO phonon is shifted to the red by 10 cm-1 from the bulk value of 345 cm-1, while the TO phonon is shifted 22 cm-1 to the blue from the bulk value of 303.7 cm-1. This shift is attributed to strain in the nanocrystals. The half width of the reflectance is dependent upon InP loading with the 2.5 vol.% samples giving 0.19 eV and the lower loaded 0.4 vol.% giving 0.17 eV for samples with the same ball diameter. Photoluminescence emission near 1.7 eV is attributed to confined InP compared with a bulk value of 1.4 eV. The energy of the emission is determined by the combined contribution of the laterally confined InP and its interaction with the opal matrix.
| Original language | English |
|---|---|
| Pages (from-to) | 269-274 |
| Number of pages | 6 |
| Journal | Materials Research Society Symposium - Proceedings |
| Volume | 452 |
| Publication status | Published - 1997 |
| Externally published | Yes |
| Event | Proceedings of the 1996 MRS Fall Meeting - Boston, MA, USA Duration: 2 Dec 1996 → 6 Dec 1996 |