InN films were grown on Si(111) wafer with AlN buffer layer by plasma-assisted molecular beam epitaxy (PAMBE). The sample went through a conventional cleaning process which involved sequential rinsing in acetone (5 mins), isopropyl alcohol (5 mins), de-ionized water (5 mins), and blown dry with nitrogen before SiO2 deposited. We used E-beam to deposit SiO2 thin film on InN. Ohmic contact (Ti) was prepared by e-beam evaporation. The system used to measure the high-frequency and low-frequency consists of Keithley 590 analyzer and Quasistatic CV meter. At last we added the capacitance-voltage study of the Si MOS structure and the research of growing high quality AlN for high quality InN.

InN thin films were grown on £^-LiAlO2 (100) by plasma-assisted molecular-beam epitaxy (PAMBE). Structural properties were investigated by reflective high-energy electron diffraction (RHEED), x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). XRD measurements showed that the crystal orientation of InN films was non-polar m-plane (11 ¡Â00). In addition, from SEM images, a striped morphology was observed along [112 ¡Â0]. Optical properties were characterized by photoluminescence (PL) spectroscopy, cathodoluminescence (CL) spectroscopy and micro-Raman scattering. Both CL/PL results revealed that InN films have a luminescence-emission peak-energy of about 0.65 eV. Carrier concentration had been determined by Hall measurements.

In this thesis , we study the surface morphology of InN thin film grown on O-polar ZnO substrate by Macular Beam Epitaxy with varied N/In flow ratio. In addition, we also observe the difference to surface of InN between the substrate have been thermal annealed or not. We analysis the samples¡¦ surface morphology and lattice structures with many different ways, such as atomic force microscope, scanning electron microscope, reflection high energy electron diffraction,transmission electron microscope, X-ray diffraction analysis and transmission spectrum measurement. From the results of SEM and AFM,while the N/In ratio increased for the process of epitaxy, InN thin film¡¦s surface would become much smooth but accompany some pin holes on the surface which indicates that there exist the interaction between substrate and InN thin film. In the X-ray diffraction analysis, the greatest value of Full Width at Half Maximum (FWHM) we get is 94.44 (arcsec) to the (0002) surface of InN that confirm pretty high quality of InN thin film grown on O-polar ZnO substrate have been made. Furthermore, the band gap measured by transmission spectrum is wider for the N/In ratio increasing either which may be caused by the formation of InxNyOz.

The excitonic transitions of a c-oriented wurtzite InN thin film, grown on sapphire substrate by plasma-assisted molecular beam epitaxy, were studied by photoreflectance (PR) measurement from 10 to 120 K. The energies of the observed features have a tendency to decrease with increasing temperature. They are assigned to excitonic transition rather than band-to-band transitions because the features can be observed only below 110 K. The justifications of such assignments are discussed in the context of binding energies of the excitons. The PR spectra of various power of pumping beam (Ppu) were also measured. The energies of the observed features become red-shifted with decreasing Ppu. This is consistent with assignment of the excitonic transition.

Zugl.: Passau, Univ., Diplomarbeit, 2002 / Hergstellt on Demand. - Literaturverz. S. 121 - 126

The optical properties of Mg-doped InN thin films grown on YSZ substrates have been investigated by photoluminescence (PL). A series of InN:Mg samples with various Mg cell temperatures (TMg) were produced by molecular beam epitaxy. The effect of Mg concentration on PL emission properties have been explored by various excitation power and temperature dependent measurements. The PL spectra as a function of excitation power exhibited a pronounce blueshift, indicating prominent band filling caused by the Burstein-Moss effect. Meanwhile, a typical redshift was observed as temperature increased due to bandgap shrinkage. The samples with TMg below 210 ˚C have a dominant peak at energy of 0.68 eV. In contrast, the PL peak emissions for films with a high TMg between 210~230 ˚C were centred near 0.6 eV. No PL emission was observed from the films with TMg above 230 ˚C. By fitting with an empirical Arrhenius equation, the activation energies yield approximately 20 meV and 15 meV for the lower and higher energy transitions, respectively. The fundamental optical properties of Zn doped InN were also examined. InN:Zn films were grown under In-rich conditions. The samples showed well defined PL emission spectra implying that the quality of the film has been improved over the Mg-doped series. The PL spectra of InN:Zn exhibited prominent features containing various emission peaks. The combination of excitation power and temperature dependent measurements supports a precise determination for the origins of the observed transitions. The comparison between the optical properties of Mg and Zn doped InN provide the motivation for more precise quantitative interpretation of p-type InN.

Among nitide sremiconductor, InN has the highest electron drift velocity and the smallest effective mass. InN has also been proven to be a narrow band gap semiconductor with a band gap energy of about 0.6-0.7 eV at room temperature. During the past few years, InN has attracted extensive attention due to is potential applications in semiconductor devices such as light-emitting diodes, lasers, and high efficiency solar cells. With the improvement of growth techniques in recently years, high quality InN films grown by plasma-assisted molecular-beam epitaxy (PAMBE) are now readily available. But there is no explicit knowledge for the physical properties of InN. In our experiment, we grow a serious of Si-doped InN with carrier concentration from 1.15 ¡Ñ 1018 cm-3 to 1.90¡Ñ1019 cm-3 by PAMBE . In this thesis we will introduce the instrument and describe the characteristics of Si-doped InN by photoluminescence, high-resolution x-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy and cathodoluminescence

This thesis discusses the crystal quality and transition of electrons and holes pairs by temperature- and power- dependent Photoluminescence (PL). With the PL spectra, we apply four kinds of Internal Quantum Efficiency (IQE) formulas for c- and m- plane III-nitride and discuss the differences of the four formulas. An analysis of IQE is performed and it is found for m-plane III-nitride being larger than c-plane III-nitride. This result confirms that characteristic m-plane structure can increase its radiative recombination.

The optical properties of Mg-doped InN thin films grown on YSZ substrates have been investigated by photoluminescence (PL). A series of InN:Mg samples with various Mg cell temperatures (TMg) were produced by molecular beam epitaxy. The effect of Mg concentration on PL emission properties have been explored by various excitation power and temperature dependent measurements. The PL spectra as a function of excitation power exhibited a pronounce blueshift, indicating prominent band filling caused by the Burstein-Moss effect. Meanwhile, a typical redshift was observed as temperature increased due to bandgap shrinkage. The samples with TMg below 210 ˚C have a dominant peak at energy of 0.68 eV. In contrast, the PL peak emissions for films with a high TMg between 210~230 ˚C were centred near 0.6 eV. No PL emission was observed from the films with TMg above 230 ˚C. By fitting with an empirical Arrhenius equation, the activation energies yield approximately 20 meV and 15 meV for the lower and higher energy transitions, respectively. The fundamental optical properties of Zn doped InN were also examined. InN:Zn films were grown under In-rich conditions. The samples showed well defined PL emission spectra implying that the quality of the film has been improved over the Mg-doped series. The PL spectra of InN:Zn exhibited prominent features containing various emission peaks. The combination of excitation power and temperature dependent measurements supports a precise determination for the origins of the observed transitions. The comparison between the optical properties of Mg and Zn doped InN provide the motivation for more precise quantitative interpretation of p-type InN.

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