Scanning tunneling microscopy images of III–V semiconductor alloys: Strain effects

Abstract

Articles you may be interested inRelaxation of a strained quantum well at a cleaved surface. Part II: Effect of cubic symmetry J. Appl. Phys. 98, 053504 (2005); 10.1063/1.2030415 Digital alloy interface grading of an InAlAs/InGaAs quantum cascade laser structure studied by cross-sectional scanning tunneling microscopy Appl. Phys. Lett. 83, 4131 (2003); 10.1063/1.1627942InGaAs/InP quantum well intermixing studied by cross-sectional scanning tunneling microscopy Scanning tunneling microscope images of lattice-matched InGaAs/InP structures were investigated using autocorrelation analysis. Correlation lengths and correlation amplitudes were calculated from constant-current empty-state images. Theoretical STM images were calculated from a model which only considered surface displacements due to strain relaxation. By comparing model and experimental correlation lengths and amplitudes it is concluded that contrast variations in constantcurrent images are dominated by strain relaxation effects. Changes in probe tip geometry and applications of this technique to study clustering in III-V alloys are also discussed.

Probe effect in scanning tunneling microscopy onSi(001)low-temperature phases

“…And c͑0,0͒ is located at the center of the image. 44 The line profiles of the autocorrelations obtained for several bias voltages are summarized in Fig. 7(b).…”

Cross-sectional scanning tunneling microscopy and spectroscopy of InGaP/GaAs heterojunctions

“…The pattern of different brightness for the P atoms reflects the distribution of neighboring In and Ga atoms. Because the cleaved surface is atomically flat, the observed contrast arises from a combination of electronic and strain effects, both associated with the presence in the alloy of clusters that are InP-rich or GaP-rich [11]. Ordering of the alloy is an important phenomenon for InGaP.…”

“…We attribute these features to In atoms. The image of In atoms will appear brighter because In atoms are bigger than Ga atoms (also the band gap of InAs is smaller than that of GaAs, which would contribute to a larger tunnel current near In atoms [11]). Indium is known to segregate on InGaP surface [13,14], and thus it will likely incorporate into following GaAs layer.…”

Scanning Tunneling Microscopy and Spectroscopy of Semiconductor Materials

“…Similar measurements were also done on embedded strained quantum-wells and superlattices (Chen et al, 1998;McKay et al, 2003), with the advantage that these structures are fully cut by the cleavage plane. Indeed, the elevation measured for cleaved quantum-dots slightly varies from dot to dot, partly because of small variations in the dot size and partly because of variations in the position of the cleavage plane across the dots.…”