Optical and x-ray diffraction studies on the incorporation of carbon as a dopant in cubic GaN

Abstract

We performed optical and x-ray diffraction experiments on carbon doped cubic-GaN samples, deposited by plasma-assisted molecular beam epitaxy on ͑001͒ GaAs substrates, for various carbon concentrations. The samples were studied by Raman, photoluminescence, and photoluminescence excitation spectroscopies. These techniques give some insight into the mechanism of carbon incorporation in the material. Detailed analysis of these spectra leads to a picture in which carbon initially enters into N vacancies producing a marked improvement in the crystalline properties of the material. At higher concentrations it also begins to enter interstitially and form C complexes, with a consequent decrease of crystalline quality. This increase and later decrease of crystalline quality of our samples with the addition of C were also detectable in x-ray diffraction scans. A model calculation of the localized vibrations of the C atom in the GaN lattice allows for the interpretation of a feature in the Raman spectrum of some samples, which reinforces this view.

Electrical and Optical Properties of Carbon Doped Cubic GaN Epilayers Grown Under Extreme Ga Excess

“…For Garich growth conditions, however, the quenching of the luminescence was neutralized and a clear spectrum was observed as seen in Fig. In stoichiometrically grown c-GaN a detailed optical and x-ray diffraction studies on the C incorporation showed a clear correlation between crystalline quality of the epilayer and C incorporated on N-site [3]. The restoration of the PL intensity at RT indicates that excess Ga flux does improve C incorporation, but it improves it with respect to all forms.…”

“…Among possible alternative acceptor dopants in GaN especially carbon has received considerable interest due to its similarity to nitrogen in atomic radius and electronegativity [1][2][3]. Previous experiments by Abernathy et al [1] showed p-type doping of GaN by carbon grown by metal organic molecular beam epitaxy (MOMBE) on GaAs substrates.…”

The Effect of Annealing Process on Some Physical Properties of GaN Thin Films with Gr Doping

“…The observed Raman spectra are characterized by the TO and LO phonons of c-GaN, 23,24 vibrational D, and G modes of graphene nanostructure. 25,26 It is known that the E2high peak turns into the band after 600 cm −1 as the amount of carbon incorporated in the structure decreases. 23 The FTIR transmission spectra of samples were performed by a Perkin Elmer Spectrum Two spectrometer in step size of 4 cm −1 .…”

Impurity-stabilized zinc-blende phase of wurtzite compounds

“…Due to the high symmetry of the cubic phase, ZB compounds usually have more isotropic properties and no spontaneous polarization [4] compared to a WZ compound. The ZB compound is also expected to have smaller effective masses, high carrier mobility, and higher doping efficiency [4], thus making it more suitable for some device applications.…”

“…The ZB compound is also expected to have smaller effective masses, high carrier mobility, and higher doping efficiency [4], thus making it more suitable for some device applications. Therefore, it is desirable in many cases to stabilize the ZB phase of a WZ compound.…”