Mapping of mechanical strain induced by thin and narrow dielectric stripes on InP surfaces

Abstract

We investigated deformation of InP that was introduced by thin, narrow, dielectric SiN x stripes on the (100) surface of InP substrates. Quantitative optical measurements were performed using two different techniques based on luminescence from the InP: first, by degree of polarization of photoluminescence; and second, by cathodoluminescence spectroscopy. The two techniques provide complementary information on deformation of the InP and thus together provide a means to evaluate approaches to simulation of the deformation owing to dielectric stripes. Ultimately, these deformations can be used to estimate changes in refractive index and gain that are a result of the stripes.

Polarized cathodoluminescence for strain measurement

“…For very thin layers, the DOP is however sensitive to film thickness due to a quantum effect. 27 The lateral resolution is the same as that of CL spectroscopy and much improved compared to the DOP of PL, 20 which enables the imaging of smaller samples such as the one with a 6 µm HM. Because light is collected over a large area, lateral resolution is limited by two physical effects: the size of the pear-shaped e-beam interaction volume and carrier diffusion.…”

“…Strain in light emitting semiconductors can also be assessed using photoluminescence (PL) 6,14 or cathodoluminescence (CL) [15][16][17][18][19][20] spectroscopy. In these techniques, the hydrostatic component of the deformation is given by the spectral shift due to electronic transitions through the material's bandgap.…”

“…38,39 Indium phosphide samples strained by thin HM stripes have already been characterized by CL spectroscopy and the DOP of PL. 20 The strain fields induced by the HM are well known and have been modelized. 20 Etched InP samples have also been characterized by CL spectroscopy 18,19 and DOP of PL 19 although in the top view only.…”

“…20 The strain fields induced by the HM are well known and have been modelized. 20 Etched InP samples have also been characterized by CL spectroscopy 18,19 and DOP of PL 19 although in the top view only. Etching is suspected to introduce stress within the patterned lines.…”

Analysis by HR-STEM of the Strain Generation in InP after SiNx Deposition and ICP Etching

“…Raman spectroscopy [5][6][7], transmission electron microscopy through dislocation characterisation [8][9][10], X-Ray diffraction [11,12], cathodoluminescence (CL) [1,13,14], using even polarized CL have been reported. However, these techniques employ indirect methods to determine strain and, in general, have low spatial resolution compared to the requirements of recent device technology processing.…”