Abstract
In this work we report results on the optical characterization of Al xGa1-xAs epitaxial layers. The layers were characterized using photoluminescence (PL) to 10 K and photoreflectance (PR) to 300 K. The AlxGa1-xAs layers resulted n-type with an electron concentration of 1×1017 cm-3and a corresponding carrier mobility of about 2200 cm2/V*s. The studies of the chemical composition by SIMS exhibit the presence of silicon, carbon and oxygen as the main residual impurities. The silicon concentration of around 1×1017 cm-3 is very close to the carrier concentration determined by the Hall-van der Pauw measurements. The 10 K photoluminescence response of the samples is strongly dependent on the growth temperature. Growth temperatures higher than 750°C were necessary to detect a reasonable photoluminescence signal. The residual oxygen detected on the samples could be responsible for the weak photoluminescence signal. Photoreflectance spectra present two transitions mainly associated to GaAs and AlxGa1-xAs. In addition, short period oscillations near the GaAs band-gap energy are observed, and are interpreted as Franz-Keldysh oscillations associated to the hole-ionized acceptor (h-A-) pair modulations. Using the AlxGa1-xAs band-gap obtained by PR, we calculated the molar fraction of aluminum, giving x = 0.221 of molar fraction.
Original language | English |
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Pages (from-to) | 245-248 |
Number of pages | 4 |
Journal | Revista Mexicana de Fisica |
Volume | 53 |
Issue number | 7 |
State | Published - Dec 2007 |
Keywords
- AlGaAs
- MOCVD
- Photoluminescence
- Photoreflectance
- Semiconductors growth