Piezoelectric Effects on the Optical Properties of GaN/Al(x)Ga(1-x)N Multiple Quantum Wells
- Sandia National Laboratories
Piezoelectric effects on the optical properties of GaN/AlGaN multiple quantum wells (MQWS) have been investigated by picosecond time-resolved photoluminescence (PL) measurements. For MQWS with well thickness 30 and 40 the excitonic transition peak positions at 10 K in continuous wave (CW) spectra are red-shifted with respect to the GaN epilayer by 17 meV and 57 meV, respectively. The time-resolved PL spectra of the 30 and 40 well MQWS reveal that the excitonic transition is in fact blue-shifted at early delay times due to quantum confinement of carriers. The spectral peak position shifts toward lower energies as the delay time increases and becomes red-shifted at longer delay times. We have demonstrated that the results described above is due to the presence of the piezoelectric field in the GaN wells of GaN/AlGaN MQWS subject to elastic strain together with screening of the photoexcited carriers. By comparing experimental and calculation results, we conclude that the piezoelectric field strength in GaN/Al.15G~.85N MQWS has a lower limit value of about 560 kV/cm: The electron and hole wave function distributions have also been obtained. The implication of our findings on the practical applications of GaN based optoelectronic devices is also discussed.
- Research Organization:
- Sandia National Laboratories, Albuquerque, NM, and Livermore, CA
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1939
- Report Number(s):
- SAND98-2511J; ON: DE00001939
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters
- Country of Publication:
- United States
- Language:
- English
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