| Summary: | 博士 === 國立成功大學 === 微電子工程研究所碩博士班 === 92 === In this dissertation, the III-N-V alloys and their heterostructures including GaNAs, InGaNAs, GaInNP, GaNAs/GaAs and InGaNAs/GaAs quantum wells have been grown by metal organic vapor phase epitaxy (MOVPE). Several material characterization techniques, such as high resolution X-ray diffraction (HRXRD), Modulation spectroscopy, photoluminescence (PL), secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM) have been performed to characterize the material quality of these epitaxial structures.
The influence of N incorporation on the band structure of (In)GaAs is described by a simple two-level “band anticrossing” model (BAC). A narrow band of highly localized N states interacts strongly with the extended conduction band edge states of the (In)GaAs host crystal. The N-induced perturbation is enhanced as the N composition increases. The resulting two levels are denotes as E+ and E�{, and the energy difference between them increases with increasing N composition. The level of E�{ is related to the fundamental bandgap transition energy of (In)GaNAs conduction band. The compositional assessment of grown In(x)Ga(1-x)N(y)As(1-y) alloys in this dissertation is also performed by using BAC model.
The local N configuration and hydrogen-induced bandgap tuning have been gave a detailed discussion in order to explain the variation of the emission wavelength of InGaNAs/GaAs quantum wells after annealing. The evolution towards more In-N bonds during annealing at elevated temperature is supposed to result in the bandgap blue shift. On the contrary, hydrogen-passivated is found to lead to a complete reversal of the drastic bandgap reduction caused by N, that is, elimination of hydrogen-passivated results in the bandgap red shift. These two factors described above can reasonably explain the variant bandgap after annealing.
The growth conditions of (In)GaNAs have been well studied in this dissertation. Many growth parameters including growth temperature, indium content, TBAs partial pressure, growth rate and the ratio of DMHy/(DMHy+TBAs) are found to effect the nitrogen incorporation. The temperature dependent photoluminescence is performed and it is found that InGaNAs has lower temperature bandgap dependence than InGaAs. The activation energy is increased with increasing nitrogen composition. In addition, In- and N-rich cluster and its abnormal optical characteristics observed in the highly nitrogen incorporated InGaNAs alloys is supposed to the highly compositional fluctuation of indium and nitrogen.
The structural and optical properties of GaInNP grown on GaAs substrate are also presented in this dissertation. The spontaneous ordering behavior and temperature dependent near band edge transition energy are also presented. The polarized- high-resolution x-ray rocking curves (HXRC), contactless electroreflectance (CER) and piezoreflectance (PzR) spectra at room temperature show anisotropic character along the [110] and directions, which can prove there exist some degree of the spontaneous ordering phenomenon in the GaInNP alloys. Ordering-induced superlattice-like microstructure observed in high-resolution transmission electron microscope (HTEM) images confirms the spontaneous ordering in the Ga0.46In0.54NxP1-x alloys.
For the device application, edge-emitting laser structures with InGaNAs quantum well active region has been grown by MOVPE and is fabricated as broad area laser diodes. The laser spectrum emits at 1.2 um, the slope efficiency is 1.94 W/A and the threshold current density is 600 A/cm2. In addition, the double heterojunction bipolar transistors (DHBTs) with low turn-on voltage by using InGaAs/GaAsP and InGaNAs as base material have been successfully fabricated and characterize. A turn-on voltage reduction of 225 mV over the conventional HBT with GaAs base layer is obtained. The device has a peak current gain of 85 and shows good high frequency characteristics of fT and fMAX are 55GHz and 45GHz, respectively.
The aim of this dissertation is to grow high quality InGaNAs quaternary alloys and quantum wells by MOVPE; the most important thing is application on the low power consumption heterojunction bipolar transistors (HBTs) and quantum well lasers toward 1.3 um emission for use as the principal devices in the transceiver module and thus contributes to the development of optical fiber communication.
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