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Introduction to Processing Methods
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2023
The chemical vapor deposition (CVD) technique enables highly homogeneous (in terms of their stoichiometry and thickness) thin films to be grown over a relatively large area. Hence this deposition technique is suitable for the manufacture of thin films for industrial applications and, indeed, many varieties of functional thin films such diamond, Si, TiN, III-V, and IV-V semiconductors have been produced by this technique. Numerous variants of CVD processes, involving thermal CVD, plasma CVD, MOCVD, and photo CVD, have been developed to date and implemented successfully. Of these, MOCVD has been used to deposit binary and multicomponent systems, in particular, such as GaAs, GaN, and superconducting thin films. CVD processes involve delivering organic metals in the form of evaporated liquids and/or sublimated solids to the deposition zone of the chamber. These gases are then decomposed by heating and reacted chemically at the substrate, resulting in the growth of the thin film. The chemical reaction can also be stimulated further by plasma and/or laser in so-called plasma- and photo-assisted MOCVD. At present, cuprate thin films have been fabricated readily by these techniques, the details of which will be presented in this chapter.
Growth Techniques
Published in Alan Owens, Semiconductor Radiation Detectors, 2019
There are several varieties of MOCVD reactors – the most common being the atmospheric MOCVD and the low-pressure MOCVD (LPMOCVD) reactors. In atmospheric MOCVD, the growth chamber is essentially at atmospheric pressure, which alleviates the problems associated with vacuum generation but at the expense of a larger gas flow rate. In LPMOCVD, the growth chamber pressure is kept low. It uses less gas than does the atmospheric case, but growth rate is then lower – in fact even slower than in MBE. The principal advantages of MOCVD are that excellent uniformity in layer thickness, composition and carrier concentration can be achieved over a large area wafer. This technique also easily lends itself to the growth of abrupt heterointerfaces, allowing complex heterostructures to be grown layer by layer. The main disadvantage is that it uses large quantities of extremely toxic gasses.
Deposition
Published in Sunipa Roy, Chandan Kumar Sarkar, MEMS and Nanotechnology for Gas Sensors, 2017
Sunipa Roy, Chandan Kumar Sarkar
It is one of the sophisticated techniques for the deposition of epitaxial layer. The schematic is shown in Figure 3.8. Metal organic chemical vapour deposition (MOCVD) is widely used in compound/alloy semiconductor materials not applicable for elemental semiconductor. The example of alloy semiconductor is SiGe, which is mostly used in making heterostructure devices, e.g. high-speed transistor. Alloy semiconductor is also referred to as compound semiconductor. The most common example of compound semiconductor is AlGaAs. For single-crystal deposition of this material, MOCVD is used. It is basically a CVD technique used to form thin films. MOCVD uses a metal organic vapour which is used as a precursor (source gas) that reacts with other reactants to form the desired film. The main advantage of MOCVD technique is that it is easy to remove volatile species from the reactor in order to avoid contamination for the next process step. It is always hard to remove solid contaminant or liquid contaminant. The excitation is generally thermal, but it may be plasma assisted.
Deposition of stoichiometry – tailored amorphous Cu-S thin films by MOCVD technique
Published in Phase Transitions, 2023
Bolutife Olofinjana, Tobiloba Grace Fabunmi, Frank Ochuko Efe, Oladepo Fasakin, Adebowale Clement Adebisi, Marcus Adebola Eleruja, Olumide Oluwole Akinwunmi, Ezekiel Oladele Bolarinwa Ajayi
Metal organic chemical vapour deposition (MOCVD) technique is a high-grade technique for the large-scale production of thin films because it can produce excellent film uniformity over a large area. It is also capable of conformal coating of arbitrary geometries with a relatively high deposition rate and good control of composition. It can also allow the use of a single solid source precursor, thereby eliminating the issue of different precursor properties in the case of multi-source precursors. In such cases, the effect of using multi-source precursors on the film’s stoichiometry, morphology and other properties will not be an issue. For the MOCVD deposition technique; temperature, gas flow rate, and arrangement of substrates are some of the deposition parameters that can affect the composition, stoichiometry, phase, structure, morphology and optoelectronic properties of the thin films. Hence the aim of this study is to deposit copper sulphide thin films of various stoichiometry via a single solid source precursor using the MOCVD technique.
Influence of oxygen partial pressure on SmBa2Cu3O7-δ film deposited by laser chemical vapor deposition
Published in Journal of Asian Ceramic Societies, 2021
Ting Wang, Rong Tu, Canlin Zhang, Song Zhang, Kaidong Wang, Takashi Goto, Lianmeng Zhang
The second generation of high-temperature superconducting tape REBCO has been attracted much attention in recent years, which has become a hot topic in present research, such as SmBa2Cu3O7−δ (SmBCO) [1,2]. SmBCO superconductor has been applied in different fields (e.g. cable transmission, motor, generator, magnetic energy storage system), which was due to its high critical temperature (Tc) and critical current density (Jc) [3,4]. The common physical deposition method of SmBCO film, such as pulsed laser deposition (PLD) [5–7], was not suitable for the large-scale commercial application, because of its high vacuum degree requirement and low deposition rate. Compared with PLD, metal organic chemical vapor deposition (MOCVD) is more adapted to industrial production of thin films. The vacuum degree requirement of MOCVD is not high, which is beneficial to reduce the cost of equipment. Moreover, the preparation process is simple and the preparation parameters are easier to control [8–10]. Therefore, the preparation of SmBCO film by MOCVD has a better application prospect. However, the deposition rate of traditional MOCVD method still could not satisfy the large-scale and commercial preparation of SmBCO films. In order to increase the deposition rate, laser has been introduced into the chemical vapor deposition [11–14]. Laser chemical vapor deposition (LCVD) can remarkably improve chemical reaction of precursors on substrates, which is conducive to enhance the deposition rate of film.
Effect of space radiation on CTJ new version multijunction solar cells
Published in Radiation Effects and Defects in Solids, 2021
B. R. Uma, Sheeja Krishnan, V. Radhakrishna, Roberta Campesato
These features are attained by CESI through the optimization in solar cell growth technology and the whole production chain of the III–V solar cells, namely: MOCVD growth at very high rates combined with a reduction of precursor consumption of the materials.Post growth (top and bottom contact metallization, Anti Reflection Coating (ARC), etc.) process sequence optimization and reduction of the process steps.High production capacity which is achieved by reducing the production time.