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Micro-Raman Spectroscopy in Self-Catalyzed Indium Phosphide Nanostructures: Morphology and Substrate Effects
摘要： We report the effect of morphology and substrate of self-catalyzed indium phosphide (InP) nanostructures on phonon vibration modes. Using liquid indium as a catalyst, we grew self-catalyzed InP nanocones and nanopillars on single crystal substrates of InP(111)B, Si(111), and Si(100) via metal-organic chemical vapor epitaxy. Due to crystal symmetry breaking in one-dimensional nanostructure, longitudinal-optical (LO) and transverse-optical (TO) phonon modes are clearly resolved with the strong anisotropic behavior. Broadening and downshift of LO phonon modes are found to be sensitive to the morphology (i.e., aspect ratio and surface-to-volume ratio) and crystal structure (i.e., Wurtzite and Zinc Blende) of the as-grown nanostructures. This work demonstrated that Raman spectroscopy provides statistical insights on the quality of as-grown nanostructures (i.e., growth orientation, crystal structures, and the presence of structural defects) without destroying samples.
关键词： VLS Process,MOVPE,InP Nanowire,Raman Spectroscopy,Self-Catalyst
更新于2025-09-04 15:30:14
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Reference Module in Materials Science and Materials Engineering || Organometallic Source Materials for III–V Epitaxy
摘要： Compound semiconductors composed from elements of the IIIrd and Vth column of the periodic system find still increasing applications in modern electronic and optoelectronic devices. Their functionality can be easily tailored by synthesizing complex multicomponent epitaxial structures. A number of deposition techniques for such structures utilize organometallic precursors because of their excellent properties in gas phase transport and deposition controllability. The most important is metal organic vapor phase epitaxy (MOVPE), sometimes also called by the more generic term metal organic chemical vapor deposition (MOCVD). MOVPE operates at pressures between 200 and 105 Pa and typically involves vapor phase mixtures of a group III organometallic and a group V hydride. Other methods like chemical beam epitaxy (CBE) have been strongly investigated in recent years. This is a high vacuum technique (ca. 10–4 Pa) which utilizes a group III organometallic and a pre-cracked group V hydride. However, it became obvious that CBE could not fulfill the expectations of the method which attempted to combine the advantages of MOVPE and molecular beam epitaxy. Hence, it is only of minor importance today. Today, MOVPE is by far the most important epitaxial method for the deposition of compound semiconductors and respective heterostructures, being widely utilized in the large scale commercial production of III–V devices, such as light emitting diodes (LEDs), laser diodes, field effect transistors (FETs), hetero bipolar transistors (HBTs) and solar cells, particularly since GaN-based LEDs are starting to revolutionize our lighting technology by the use of highly efficient white LEDs (solid-state lighting). MOVPE has the advantages of large area growth, precise control of film thickness, and doping and superior conformal step coverage of small surface features. In this article, the organometallic precursors as key elements of these techniques will be discussed with respect to their synthesis, chemical and physical properties and their applications in the epitaxial growth of III–V compound semiconductors.
关键词： semiconductor devices,MOVPE,CBE,III–V epitaxy,Organometallic precursors
更新于2025-09-04 15:30:14
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Axial p–n Junctions in GaN Microrods
摘要： GaN microrods with an axial p–n junction are grown by metal-organic vapor phase epitaxy (MOVPE). Scanning electron microscopy in combination with cathodoluminescence measurements have been performed to visualize the microrod sections consisting of n- and p-type GaN and the p–n junction. Current–voltage measurements are carried out between different microrod sections to prove the successful formation of a p–n junction. Photovoltaic and photodetecting properties have been determined by illumination of the p–n junction with a UV laser. The shorter p-type sections in axial microrods and the presence of large diameter rods suggest a growth mode change from vertical to lateral growth during p-type deposition.
关键词： microrods,cathodoluminescence,MOVPE,GaN
更新于2025-09-04 15:30:14