Growth oscillations with monolayer periodicity monitored by ellipsometry during metalorganic vapor phase epitaxy of GaAs(001)

Abstract

In this letter we report on the observation of growth oscillations with monolayer periodicity by ellipsometry. An oscillation amplitude of δ〈ε1〉=0.05 was measured using an optimized spectroscopic in situ ellipsometer whose wavelength was tuned to the 2.65 eV resonance energy of the arsenic dimers covering the GaAs (001) growth surface. The monolayer periodicity was verified by parallel monitoring of the growth with reflectance anisotropy spectroscopy (RAS).

Development and control of MOVPE growth processes for devices using reflectance anisotropy spectroscopy and normalized reflectance

“…Real composition control using ellipsometry has been reported by a direct control of the TMIn mass flow controller (MFC) via the ellipsometry computer for the growth of InGaAs on InP [22] and InGaP on GaAs [23]. However, the application of an ellipsometer at a MOVPE system is much more difficult due the large angle of incidence and the extreme alignment sensitivity as compared to the normal-incidence RA and NR techniques [24].…”

Strain Oscillations Probed with Light

“…Even growth oscillations with monolayer periodicity have been reported for the GaAs(100) surface [6,7]. In this case, however, a surface resonant electronic transition related to the presence of Ga or As dimers is probed, whose concentration is affected by the (oscillating) density of surface steps during growth.…”

Pulsed Laser Deposition (PLD)

“…Typically connected to the PLD chamber, RHEED systems are often equipped with a differentiated vacuum pumping unit for in situ observations during thin-film deposition under a gaseous ambience [10]. Several other in situ characterization techniques, including low-energy electron diffraction, X-ray photoelectron spectroscopy, Auger electron spectroscopy, coaxial impact collision ion scattering spectroscopy, scanning probe microscope, and optical measurements, such as spectroscopic ellipsometry, have also been implemented in PLD systems [13][14][15][16][17]. Laser molecular beam epitaxy (MBE) (Figure 8.2) [11,12], which couples in situ RHEED observation with PLD for epitaxial growth, has proved to enable real-time growth control at an atomic-layer scale.…”

“…The crystal orientation of the films depended on the background and nitrogen partial pressures as well as growth temperature. TEM observations also revealed that in-plane AlN jj [11][12][13][14][15][16][17][18][19][20] sapphire and [11][12][13][14][15][16][17][18][19][20] AlN jj [11][12][13][14][15][16][17][18][19][20] 6H-SiC were epitaxial relationships between AlN and substrate materials, respectively. Figure 8.17 shows X-ray diffraction scans of AlN films grown on sapphire (0001) and 6H-SiC (0001).…”