| Summary: | 碩士 === 國立彰化師範大學 === 電子工程學系 === 99 === We present the optical and electrical studies of III-V compound semiconductors and high electron mobility transistor (HEMT) structures using temperature-dependent photoluminescence (PL), reflectance (R), absorption, and Hall measurement. these samples were grown by metal-organic chemical vapor deposition (MOCVD) on GaAs substrate and designated as A (III-V compound semiconductors) and B (HEMT structures). In PL spectra of sample A, the features of InGaAs film with different indium composition were investigated, two optical features identified as band to band and donor to acceptor related were observed. In the absorption spectra, the absorption edges coincided with the band to band related of PL spectra. In addition to PL, the reflectance and absorption measurements have also been done. And we found that as increasing the In composition, it seems to reveal another absorption edge at higher energy. For understanding the reason of an additional absorption edge at the higher energy, a depth profiling of secondary ion mass spectrometer was performed. In sample B, the carrier concentration of caped and capless HEMT structures were investigated, two optical features identified as 11H and 21H were observed. We extracted the quantitative energy information through a phenomenological line-shape model to the PL spectra and estimated the carrier concentration using theoretical calculation. In hall measurements, a parallel conducting problem occurs in caped sample, which significantly affects the result of carrier concentration. However, the existence of cap layer do not affect its PL spectra. Therefore, using theoretical calculation estimated the carrier concentration from the PL spectra is convenient and nondestructive.
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