Investigation of molecular-beam epitaxially grown CdTe on GaAs by x-ray photoelectron spectroscopy

Waag, A.; Wu, Yan; Bicknell-Tassius, R.N.; Gonser‐Buntrock, C.; Landwehr, G.

doi:10.1063/1.347118

Cited by 13 publications

(9 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Te/M ratio evolved with the similar tendency as that of the film deposited by CSS, which was 2.5 [21]. In a CdTe film deposited by MBE on GaAs at the substrate temperature of 563 K, Waag et al [14] found that the Te/M ratio was below 40/60 when the film thickness was less than 10 Å and it approached to 1 as the film being thickened. The base pressures during deposition of these films via different methods vary from ultrahigh (MBE), middle (VE), to low vacuum conditions (CSS); the substrate temperatures vary from room temperature (VE) to over 800 K (CSS), and the source-substrate distances vary from a few millimeters (CSS) to dozens of millimeters (VE).…”

Section: Resultsmentioning

confidence: 72%

“…Interfacial composition and structural properties play very important parts in thin film growth and the final device performance [14][15][16][17][18][19]. A thorough understanding of the interfaces between CdZnTe films and the substrates will help with improving the film quality and further advancing their applications.…”

Section: Introductionmentioning

confidence: 99%

“…Te aggregation at the initial growth has been observed by many researchers when compound sources are involved [8,14,17,18]. The reactions between Te atoms and the substrates play an important part in the epitaxy of CdTe films [8,14,18].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study of Te aggregation at the initial growth stage of CdZnTe films deposited by CSS

Gao

Wang

et al. 2012

Appl. Phys. A

View full text Add to dashboard Cite

Te aggregation at the initial growth stage of CdZnTe films deposited by close-spaced sublimation (CSS) is studied with the combination of energy dispersive spectroscopy (EDS) and high resolution transmission electron microscopy (TEM). Te atoms aggregate in the form of Terich amorphous layers, and then these layers grow into stoichiometric and crystalline compounds through interdiffusion as the films thickened. Te aggregation is led by the high dissociation energy of Te-Te bond and the less volatile nature of Te 2 molecules than Cd and Zn molecules absorbed on the substrate.

show abstract

Section: Resultsmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study of Te aggregation at the initial growth stage of CdZnTe films deposited by CSS

Gao

Wang

et al. 2012

Appl. Phys. A

View full text Add to dashboard Cite

show abstract

“…The use of in situ x-ray photoelectron spectroscopy (XPS) helped to ensure that only optimally cleaned surfaces were used in the following investigations. 18,19 A RIBER model CER 606 electron gun with model ACE 1010 controlling electronics was used as a source of high-energy electrons both for the RHEED patterns and in the investigations of the effects of high-energy electrons on the epitaxial growth surfaces. In the present experiments, the acceleration voltage of the electron gun was about 9 kV, the electron current was about 20 j1A, and the beam was focused as small as possible.…”

Section: Methodsmentioning

confidence: 99%

The effects of laser illumination and high energy electrons on molecular-beam epitaxial growth of CdTe

Becker

Waag

et al. 1991

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

We report the results of a detailed investigation on the Te-stabilized (2X 1) and the Cdstabilized c(2 X 2) surfaces of (100) CdTe substrates. The investigation demonstrates for the first time that both laser illumination and, to a greater extent, high-energy electron irradiation increase the Te desorption and reduce the Cd desorption from (100) CdTe surfaces. Thus it is possible by choosing the proper growth temperature and photon or electron fluxes to change the surface reconstruction from the normally Te-stabilized to a Cd-stabilized phase. J. INTRODUCTIONThe use of light to improve the quality of molecularbeam epitaxially (MBE) grown II-VI materials and to enhance substitutional doping is one of the recent exciting developments in the growth of compound semiconductors. Bicknell et al. and Hwang et al. I -3 have grown high-quality CdTe with this photoassisted molecular-beam epitaxy (PAMBE) method. Their best undoped n-type CdTe had a mobility of 6600 cm 2 ;V s and their In-doped CdTe (n = 2 X 10 16 cm -3 at 300 K) had a mobility of 2380 cm 2 ;V s. This is in contrast to conventional MBE-grown CdTe which is semi-insulating. 4 Due to the availability of high-quality conducting epilayers of CdTe, all thin-film CdTe electronic devices have been recently produced, i.e., pn junctions and metal-semiconductor field-effect transistors. 5,6 Photoassisted molecular-beam epitaxy has also been applied to the growth of highly conducting, dilute magnetic semiconductor epitaxiallayers and superlattices.7 Recently, this new technique has been applied to the growth of mercury-based U-VI materials. Koestner et al. have grown (lOO) and (211) HgCdTe epitaxiallayers using PAMBE which exhibited a low dislocation density, 1-2 X IOS and 3-5 X 10 4 cm -2, respectively, over a wider range of growth conditions than is possible by conventional MBE.8 Similarly Myers et al. have grown some of the best epitaxial HgCdTe to date with extremely narrow x-ray double-crystal rocking curves and very high carrier mobility.9 They reported dislocation line densities for (211) HgCdTe as low as 5 X 10 4 cm -2. Their reported electron mobilities of the (100) HgCdTe epilayer are as high as 8.5 X lOS cm 2 ;V s for samples with 13% Cd, and are 4 X 10 5 cm 2 IV s for a sample with 20% Cd.The above results may be summarized in general by stating that photoillumination during MBE growth greatly improves the structural properties as well as the electrical properties of the epitaxial layers that are grown using the photoassisted MBE technique. Therefore, detailed investigations into the mechanisms of how light affects the growing surface is of utmost importance. If the mechanism of the photoassisted MBE process is understood in detail it should a) Permanent address: Institute of Physics, Chinese Academy of Sciences, Bcijing. People's Republic of China.be easier to optimize the technique for anyone material and easier to apply it to other materials systems. In fact, it has been recently reported that UV light illumination can enhance the migration of adsorba...

show abstract

“…Table 2) thus showing that a number of substrates do not fulfill the requirement of a high resistivity. Also, the structural quality is often not quite satisfactory [27]. The values of the conductivity O"E of the epitaxial layers compiled in Table 2 were determined at room temperature by the van der Pauw method [28] which is fairly reliable for our samples which all are n-type.…”

Section: Analysis Of the Experimental Datamentioning

confidence: 99%

Contactless measurement of the conductivity of II?VI epitaxial layers by means of the partially filled waveguide method

et al. 1992

View full text Add to dashboard Cite

Abstract. We report the contactless determination of the conductivity, the mobility and the carrier concentration of II-VI semiconductors by means of the technique of the partially filled waveguide at a microwave frequency of 9 GHz. The samples are CdllgTe epitaxial layers, grown on CdZnTe substrates by molecular beam epitaxy. The conductivity is determined from the transmission coefficient of the sample in the partially filled waveguide. For the analysis of the experimental data, the complex transmission coefficient is calculated by a rigorous multi-mode matching procedure. By varying the conductivity of the sample, we obtain an optimum fit of the calculated data to the experimental results. Comparison with conductivity data determined by the van der Pauw method shows that our method allows to measure the conductivity with good accuracy. The behaviour of the transmission coefficient of the sample is discussed in dependence on the layer conductivity, the layer thickness and the dielectric constant of the substrate. The calculations require to consider in detail the distribution of the electromagnetic fields in the sample region. The usual assumption of a hardly disturbed TEIO mode cannot be used in our case.By applying a magnetic field in extraordinary Voigt configuration. galvanomagnetic measurements have been carried Qut which yield the mobility and thus the carrier concentration. These results are also in good agreement with van der Pauw transport measurements.. 72.80.Ey, 78.70.Gq [here is a growing interest in II-VI semiconductors bepuse of their potential applications as devices in the areas ~f opto-electronics and photonics. Their bandgap spans a !wide range from the infrared (CdHgTe) to the violet (ZnS). (consequently, some members of this semiconcutors family lire used as sensitive infrared detectors while others will be iauitable for the realization of LED's etc. with light emission pn the blue part of the visible spectrum. But a number of F hnical problems have to be overcome before we know . w to fabricate reliable devices of this kind. A major step i towards solving these problems is the growth of high quality epitaxial films by means of a new, recently developed growth process, namely photoassisted molecular beam epitaxy (PAMBE) [1,2]. The growth of such films has always been difficult because of the tendency of U-VI compounds to incorporate local defects such as vacancies, interstilials and impurities [3). After the growth of the epitaxial layers, it is absolutely necessary to characterize the samples, i.e. to measure the conductivity, the Hall effect etc., in order to control and optimize their quality with sufficient accuracy in a short time. The knowledge of the electrical transport parameters is especially required in the field of device fabrication. Unfortunately, that is often hampered by the fact that it is difficult or sometimes even impossible to obtain good ohmic contacts. One reason for this is the well known tendency of self-compensation in II-VI compounds.To avoid these problems. a...

show abstract

Investigation of molecular-beam epitaxially grown CdTe on GaAs by x-ray photoelectron spectroscopy

Cited by 13 publications

References 30 publications

Study of Te aggregation at the initial growth stage of CdZnTe films deposited by CSS

Study of Te aggregation at the initial growth stage of CdZnTe films deposited by CSS

The effects of laser illumination and high energy electrons on molecular-beam epitaxial growth of CdTe

Contactless measurement of the conductivity of II?VI epitaxial layers by means of the partially filled waveguide method

Contact Info

Product

Resources

About