Type I–Type II Transition of Self-Assembled In0.55Al0.45As/Al0.5Ga0.5As Quantum Dots

✍ Scribed by G.H. Li; Y. Chen; Z.L. Fung; K. Ding; H.X. Han; W. Zhou; Z.G. Wang

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 165 KB
• Volume: 223
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/1521-3951(200101)223:1<157::aid-pssb157>3.0.co;2-r

✦ Synopsis

The photoluminescence (PL) of In 0.55 Al 0.45 As/Al 0.5 Ga 0.5 As self-assembled quantum dots has been measured at 15 and 80 K under hydrostatic pressure. The lateral size of the dots ranges from 7 to 62 nm. The emissions from the dots with 26, 52 and 62 nm size have a blue shift under pressure, indicating that these quantum dots have the normal type-I structure with lowest conduction band at the G-valley. However, the PL peak of dots with 7 nm diameter moves to lower energy with increasing pressure. It is a typical character for the X-related transition. Then these small dots have a type-II structure with the X-valley as the lowest conduction level. An envelope-function calculation confirms that the G-like exciton transition energy will rise above the X-like transition energy in the In 0.55 Al 0.45 As/Al 0.5 Ga 0.5 As structure if the dot size is small enough.