Abstract
The strucutral and optical properties of undoped AlGaN/GaN single heterojunctions (HJs) were studied by means of high-resolution x-ray diffraction, photoluminescence (PL), cathodoluminescence (CL), and time-resolved PL spectroscopy. An additional two-dimensional electron gas (2DEG)-related PL and CL emission appeared at about 40 meV below the GaN band-edge emission energy and persisted up to about 100 K, while this peak disappeared when the top AlGaN layer was removed by reactive ion etching. Depth-resolved CL spectra reveal the presence of a 2DEG at the heterointerface. The additional PL and CL emission below the GaN band-edge emission is attributed to the recombination between photogenerated holes and electrons confined at 2DEG states in the triangular-shaped interface potential. For the 2DEG emission, we observed an about 50-ps delayed rise time than the GaN and AlGaN emissions by using time-resolved PL, indicating effective carrier transfer from the GaN flatband and AlGaN regions to the heterointerface. From the results, we explained the optical properties and carrier recombination dynamics of 2DEG, GaN, and AlGaN emissions in undoped AlGaN/GaN single HJs.
| Original language | English |
|---|---|
| Pages (from-to) | 2109-2112 |
| Number of pages | 4 |
| Journal | Physica Status Solidi (C) Current Topics in Solid State Physics |
| Volume | 3 |
| DOIs | |
| State | Published - 2006 |
| Event | 6th International Conference on Nitride Semiconductors, ICNS-6 - Bremen, Germany Duration: 28 Aug 2005 → 2 Sep 2005 |