Epitaxial PLD

Table 7.4. Results of high-resolution XRD analysis of several series of epitaxial PLD ZnO thin films grown on c-plane, a-plane, and r-plane sapphire at about 650° C substrate temperature, taken from [47]...

Fig. 102. Variation of optical transmittance (at 635 nm) as afunction of electrical resistivity during hydrogen loading and deloading of Pd (10 nm) capped (i) Epitaxial MBE, (ii) Epitaxial PLD and (iii) Nanocrystalline PLD Y films...

Fig. 4. Energy below the conduction band of levels reported in the literature for GaP. States are arranged from top to bottom chronologically, then by author. At the left is an indication of the method of sample growth or preparation liquid phase epitaxy (LPE), liquid encapsulated Czochralski (LEC), irradiated with 1-MeV electrons (1-MeV e), and vapor phase epitaxy (VPE). Next to this the experimental method is listed photoluminescence (PL), photoluminescence decay time (PLD), junction photocurrent (PCUR), photocapacitance (PCAP), transient capacitance (TCAP), thermally stimulated current (TSC), transient junction dark current (TC), deep level transient spectroscopy (DLTS), photoconductivity (PC), and optical absorption (OA).

The preparation of c-axis aligned or even epitaxial RNi2B2C thin films has been performed using both, pulsed laser deposition (PLD Cimberle et al., 1997 Hase et al., 1997) and magnetron sputtering technique (Arisawa et al., 1994 Andreone... 

For A n = 0.2-50eV, surface penetration into the first monolayers reduces the temperature for epitaxy and yields a higher density of structures. These processes dominate in sputtering and PLD at higher background pressures of 0.05-0.5mbar. 

The typical parameters for the PLD of epitaxial ZnO-based thin films on sapphire including information about target preparation are listed in Table 7.3. Within the range of these software controlled parameters, the properties of the deposited films differ widely, as will be shown in Sect. 7.4. Beside the parameters listed in Table 7.3, the film properties will be influenced furthermore by a few more internal effects, which will be listed and discussed in the following according to the scheme effect/problem-cause-solution. Only the careful consideration of all these hidden effects by experienced operators can ensure the highest quality and reproducibility of PLD grown films. 

Table 7.3. Typical PLD parameters for epitaxial ZnO-based thin films, using an excimer laser LPX 305 (see Table 7.1), and the PLD chamber described in Table 7.2...

Mixed metal oxides can be addressed as belonging to three main fields, namely superconducting metal oxides (SMOs) (Section V.D.l), transparent conductive oxides (TCOs) (Section V.D.2) and ferroelectric oxides (Section V.D.3). The synthesis procedures for mixed metal oxides include sintering, sol-gel, PLD or laser ablation, sputtering evaporation, MBE, MOVPE (metal-organic vapor-phase epitaxy), OMVPE (organometallic vapor-phase epitaxy) and CVD in particular. 

IBAD, as shown in Figure 4-10, as applied to compound semiconductors, also is a relatively new technique, and as with PLD is primarily under development to produce films which have no other direct and convenient means of fabrication. In IBAD, an ion beam is formed and directed at the deposition plane. One or more ion beams may be combined with gas or plasma fluxes, as well as evaporator hearths or other sources. This technique also has been used to form epitaxial films. 

Lasers and electron beams. These can be used to provide local heating or to heat small quantities. The temperature control is not great, but these techniques are very versatile. Electron beams are used to vaporize silicon for thin-film deposition using molecular-beam epitaxy. A focused laser beam is the basis of the pulsed-laser deposition (PLD) thin-film growth technique (Chapter 28). 

Thin-film reaction couples can be prepared by growing thin films on a specially prepared substrate PLD works well for the deposition but molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) could be used equally well. 

If Cr-Si-N crystals which have dissolved Si atoms into the B1 lattice can be prepared, the improvement of hardness can be expected with the distortion of the crystal lattice such as Cr(N,0) . It has been reported that CrN is epitaxially grown on MgO (001) substrates . Pulsed laser deposition (PLD) is a good method to control the composition of thin films, which is ideal to deposit Cr-Si-N with precise Si content control. However, there are no reports that Cr-Si-N was prepared by PLD. In addition, the solubility of Si atoms into CrN lattice has not been investigated. In this work, we prepared Cr-Si-N thin films on Si(lOO) and MgO(lOO) substrates by PLD and investigated the solid solution of Si atoms into CrN lattice for improvement of the hardness. 

From the results of deposition of Cr-Si-N thin films by PLD on the characterizations, it was found that CrN and Cr-Si-N was formed as B1 crystals epitaxially grown on MgO(lOO) substrates and these thin films had Si content of 0 and 5.0 at.%, respectively. On the other hand, CrN and Cr-Si-N thin films on Si(lOO) substrates were poly ystalline. The Cr-Si-N thin film on MgO(lOO) substrate showed that the Cr content was less than that of N. This result suggested that (Cr,Si)N phase was formed. Furthermore, adding Si into CrN on MgO(lOO) substrate, the hardness was increased finm 29 to 36 GPa. This result implied the effect of solid solution hardening for solubility of Si atoms in the CrN lattice as (Cr,Si)N. 

Several techniques can be used for the growth of epitaxial thin films and heterostructures [17,18]. In the following, we will discuss only the physical vapor deposition methods mainly used to grow complex oxides, that is, molecular beam epitaxy (MBE), pulsed laser deposition (PLD), and sputtering. 

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