MOVPE growth investigations of doping and ordering in AlGaAs and GaInP with reflectance anisotropy spectroscopy

Krahmer, C.; Philippens, M.; Schubert, M.; Streubel, K.

doi:10.1016/j.jcrysgro.2006.10.001

Cited by 10 publications

(6 citation statements)

References 13 publications

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“…4 As there is hardly any size-mismatch in AlGaAs, long-range order has not been widely observed. Nevertheless, Krahmer et al 5 reported evidence of a direct-indirect conduction band transition for x = 0.4 in Al x Ga 1Àx As by using reflectance anisotropy spectrometry, indicating an increase in order. They report that doping, temperature and substrate orientation all affect the anisotropy of the lattice, but did not quantify this in terms of an order parameter.…”

Section: Introductionmentioning

confidence: 99%

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

Knijn

Bentum

Eck

et al. 2010

Phys. Chem. Chem. Phys.

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We have conducted (75)As and (69)Ga Nuclear Magnetic Resonance (NMR) experiments to investigate order/disorder in Al(x)Ga(1-x)As lift-off films with x∼ 0.297 and 0.489. We were able to identify all possible As(Al(n)Ga(4-n)) sites with n = 0-4 coordinations in (75)As NMR spectra using spin-echo experiments at 18.8 Tesla. This was achieved by employing high rf field strengths using a small solenoid coil and an NMR probe specifically designed for this purpose. Spectral deconvolution, using an evolutionary algorithm, complies with the absence of long-range order if a CuAu based order parameter is imposed. An unconstrained fit shows a deviation of the statistics imposed by this type of ordering. The occupational disorder in the Ga and Al positions is reflected in a distribution of the Electric Field Gradients (EFGs) experienced at the different arsenic sites. We established that this can be modelled by summing the effects of the first coordination sphere and a Czjzek type distribution resulting from the compositional variation in the Al/Ga sub-lattice in the higher coordination spheres. (69)Ga 3QMAS and nutation data exclude the presence of highly symmetric sites and also show a distribution in EFG. The experimentally obtained quadrupolar interactions are in good agreement with calculations based on Density Functional Theory (DFT). Using additivity of EFG tensors arising from distant charge perturbations, we could use DFT to model the EFG distributions of the n = 0-4 sites, reproducing the Czjzek and extended Czjzek distributions that were found experimentally. On the basis of these calculations we conclude that the (75)As quadrupolar interaction is sensitive to compositional modulations up to the 7th coordination shell in these systems.

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Section: Introductionmentioning

confidence: 99%

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

Knijn

Bentum

Eck

et al. 2010

Phys. Chem. Chem. Phys.

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“…The doping concentration of the p-GaAs layer is slightly above 10 19 cm −3 , whereas that for the n-GaAs layer is about 7·10 18 cm −3 . The RAS spectrum for intrinsic GaAs exhibits the typical signature due to the anisotropies on the semiconductor surface [ 23 , 24 , 25 ]. The RAS spectrum of the p-GaAs layer has a higher RAS signal for all photon energies.…”

Section: Resultsmentioning

confidence: 99%

Doped or Quantum-Dot Layers as In Situ Etch-Stop Indicators for III/V Semiconductor Reactive Ion Etching (RIE) Using Reflectance Anisotropy Spectroscopy (RAS)

et al. 2021

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Reflectance anisotropy spectroscopy (RAS), which was originally invented to monitor epitaxial growth, can—as we have previously shown—also be used to monitor the reactive ion etching of III/V semiconductor samples in situ and in real time, as long as the etching rate is not too high and the abrasion at the etch front is not totally chaotic. Moreover, we have proven that—using RAS equipment and optical Fabry‒Perot oscillations due to the ever-shrinking thickness of the uppermost etched layer—the in situ etch-depth resolution can be as good as ±0.8 nm, employing a Vernier-scale type measurement and evaluation procedure. Nominally, this amounts to ±1.3 lattice constants in our exemplary material system, AlGaAsSb, on a GaAs or GaSb substrate. In this contribution, we show that resolutions of about ±5.6 nm can be reliably achieved without a Vernier scale protocol by employing thin doped layers or sharp interfaces between differently doped layers or quantum-dot (QD) layers as etch-stop indicators. These indicator layers can either be added to the device layer design on purpose or be part of it incidentally due to the functionality of the device. For typical etch rates in the range of 0.7 to 1.3 nm/s (that is, about 40 to 80 nm/min), the RAS spectrum will show a distinct change even for very thin indicator layers, which allows for the precise termination of the etch run.

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“…Equation (4) establishes the condition of continuity at each interface, and Eq. (5) represents the phase change after light has traveled a distance d k through layer k. The reflection coefficient is simply obtained by multiplying the propagation matrices.…”

Section: Resultsmentioning

confidence: 99%

“…For this purpose, in situ optical techniques such as reflectance difference spectroscopy (RDS), 1,2 reflectance anisotropy spectroscopy (RAS), 3,4 spectroscopic ellipsometry (SE), 5,6 surface photoabsorption (SPA), 7,8 laser reflectometry (LR), 9,10 and spectral reflectance (SR) [11][12][13] have received considerable attention during recent years. Their use as nondestructive and real-time monitoring tools is of great advantage for growth process analysis.…”

Section: Manufacturingmentioning

confidence: 99%

In Situ Spectral Reflectance Investigation of InAs/GaAs Heterostructures Grown by MOVPE

Massoudi

Habchi

Rebey

et al. 2011

Journal of Elec Materi

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Metalorganic vapor-phase epitaxy of InAs/GaAs heterostructures was monitored in situ by spectral reflectance in the wavelength range from 600 nm to 1000 nm. Three-dimensional (3D) plots of reflectivity as a function of time and wavelength were used to determine the growth rate evolution. Theoretical simulation of reflectivity signals was carried out by combining a transfer matrix method and a multi-sublayer model. In spite of fixed growth parameters, there was temporal variation of the growth rate. By adjusting simulated reflectivity curves, optical constants of the InAs layer at 450°C were determined. The E 1 critical point energy was also found experimentally at this temperature. Good agreement with calculated values is obtained.

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MOVPE growth investigations of doping and ordering in AlGaAs and GaInP with reflectance anisotropy spectroscopy

Cited by 10 publications

References 13 publications

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

Doped or Quantum-Dot Layers as In Situ Etch-Stop Indicators for III/V Semiconductor Reactive Ion Etching (RIE) Using Reflectance Anisotropy Spectroscopy (RAS)

In Situ Spectral Reflectance Investigation of InAs/GaAs Heterostructures Grown by MOVPE

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