Atomic Layer-by-Layer MOCVD of Complex Metal Oxides and In Situ Process Monitoring

Abstract

The progress of atomic layer-by-layer metal±organic (MO) CVD of complex metal oxides and related growth technologies is reviewed. Atomic layer-by-layer MOCVD produces thin films of complex metal oxides that are of high crystalline quality, with a very smooth surface. These features allow us to fabricate modulated structures on an atomic scale, such as d-doping, superlattice structure, and heterostructures. A common problem of oxide MOCVD is poor controllability of the growth conditions, mainly caused by instability of precursor supply. To overcome this problem, new precursors have been developed, and in situ process monitoring, using an ultrasonic transducer and spectroscopic ellipsometry, is applied during the MOCVD process. The reproducibility of MOCVD growth has been improved significantly.

Digital model for X-ray diffraction with application to composition and strain determination in strained InAs/GaSb superlattices

“…[19][20][21] The performances of devices built upon superlattices can be highly sensitive to the quality of superlattices formed during growth. 22 The common techniques used to grow superlattices are MBE, 23 sputtering deposition, 24 metaloxide chemical vapor deposition (MOCVD), 25 and pulsed laser deposition (PLD). 26 Among them, MBE is often the method of choice for growth of high quality superlattices because its low deposition rates allow a precise manipulation and monitoring of epitaxial growth.…”

Nondispersive Infrared Gas Analyzer for Vapor Density Measurements of a Carbonyl-Containing Organometallic Cobalt Precursor

“…1–11 Schemes for improving control of precursor delivery in vapor deposition processes fall within two main categories: enhanced precursor delivery system design; 5,9,12–18 and closed loop control of precursor flux. 2–4,6,19–25 Metrologies that provide the time-dependent precursor concentration can contribute to both methods. In the case of delivery system design, precursor concentration measurement is desirable for efficient characterization of the flow system.…”

“…Acoustic methods are commercially available and have been utilized for decades. 2–4,6,9,17,18,21,23–31 However, these methods tend to be limited to pressures above ≈6.7 kPa (50 Torr), 30 making them unsuitable for many low-pressure CVD and ALD processes. A range of optical methods have been utilized that have the potential to operate at lower pressures and with more flexibility in the sampling configuration than acoustic methods.…”

Multi-component oxide nanosystems by Chemical Vapor Deposition and related routes: challenges and perspectives

“…63,[74][75][76][77][78][79][80] The unique tailoring of nanomaterial morphology, enabled by a careful control of operational parameters under non-equilibrium conditions, has been exploited for the fabrication of various systems, from inorganic oxides to carbonbased systems, in the form of nanopowders, coatings, nanocrystals, nanorods (NRs) and nanotubes (NTs). 7,8,56,57,63,74,[78][79][80][81][82][83][84][85][86][87][88] Beyond the great interest devoted to CVD precursor design and synthesis, [89][90][91][92][93] intensive efforts have led to the development of a large variety of CVD processes, related to different precursor delivery and operational/activation modes. These involve atmospheric or low pressure-CVD (AP-CVD or LP-CVD), [78][79][80]94 fluidized-bed CVD, liquid injection-CVD (LI-CVD), 75,76 aerosol assisted-CVD (AA-CVD) 95 and plasma enhanced-CVD (PE-CVD).…”