Direct determination of intrinsic In_x Ga_1–xP (x = 0.49) band‐gap deformation potentials by cathodoluminescence piezo‐spectroscopy

Abstract

We determined to a degree of precision the complete set of three deformation potentials of zinc‐blende‐like (intrinsic) Inx Ga1–x P (x = 0.49) and found that their variation with chemical composition does not follow a linear rule‐of‐mixture between values of InP and GaP, as usually assumed in the published literature. Measurements were made according to a microscopic cathodoluminescence piezo‐spectroscopic (CL/ PS) procedure, previously calibrated for paradigm materials, which deformation potentials are known according to macroscopic calibration calibration procedures. The procedure followed in this study allowed us to obtain the desired deformation potential values directly on a thin film (i.e., without the need of a bulk sample), by exploiting the high spatial resolution of the electron probe. Microscopic strain fields were used, which were preliminary introduced by a pyramidal indentation print on the surface of the epitaxially grown film. The methodology enabled accurate deformation potential assessments in small material volumes for both tensile and compressive stress fields. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Nanometer‐scale cathodoluminescence analysis of GaAs and its application to the assessment of laser diode

“…(18)–(20) can be used to determine the hydrostatic deformation potential, a , the deviatoric deformation potential, b , and the shear deformation potential, d , which represent the shift of the energy band gravity center with strain, and the dependency of the valence band splitting with hydrostatic and shear strain of the crystal, respectively. A controlled (surface) stress field can be obtained by printing a pyramidal indentation mark on the material surface with taking care that the diagonals of the print are parallel to the cleavage directions of the investigated crystal 8–10. It should be noted that the stress field generated around an indentation print, as well as any biaxial surface stress state, can be considered as the superposition of an equi‐biaxial, σ b , and a uniaxial stress state, σ u .…”

“…However, it is important to keep the method updated and ready to exploit theoretical and computational advances. In our previous CL studies of semiconductors 4, 6–10, efforts were made in tracking back the CL signal to fundamental electronic properties of the semiconductors, like as self‐absorption 7 or strain 4, 6–10. Surprisingly, we noticed that direct measurements of deformation potentials, namely the intrinsic parameters governing light emission under strain fields, in many semiconducting compounds of technological interest have been conspicuously lacking in the available literature.…”

“…Surprisingly, we noticed that direct measurements of deformation potentials, namely the intrinsic parameters governing light emission under strain fields, in many semiconducting compounds of technological interest have been conspicuously lacking in the available literature. This unfortunate circumstance gave us no other choice than systematically measuring such experimental parameters with developing improved CL calibration methods to be applied in situ in the FEG‐SEM 9, 10. Quantitative assessments of deformation potentials were, e.g ., given for Si‐doped GaAs, n ‐Al 0.25 Ga 0.75 As, and i ‐In 0.41 Ga 0.59 P, taking advantage of locally developed (microscopic) residual stress fields reproducibly created in situ directly on the devices.…”