Strain Determination in Quasi-Lattice-Matched LWIR HgCdTe/CdZnTe Layers

X-ray Diffraction Residual Stress Measurement at Room Temperature and 77 K in a Microelectronic Multi-layered Single-Crystal Structure Used for Infrared Detection

“…A.-L. LEBAUDY , 1,2,3,4 R. PESCI, 1 The electronic assembly considered in this study is an infrared (IR) detector consisting of different layers, including (111) CdHgTe and (100) silicon single crystals. The processing steps and the low working temperature (77 K) induce thermomechanical stresses that can affect the reliability of the thin and brittle CdHgTe detection circuit and lead to failure.…”

“…A few authors have made some experimental measurements to quantify the strain induced in epitaxy-grown CdHgTe, but none on complete multilayer assemblies. 2,3 Finite element modellings have been rather widely used in order to predict the appearance of stresses under thermal loadings. 4,5 However, the material properties are not well known, especially at low temperature (elastic constants, thermal expansion coefficient), and the complexity of electronic assemblies imposes many assumptions in order to obtain acceptable computing times.…”

Multilayer CdHgTe-based infrared detector: 2D/3D microtomography, synchrotron emission and finite element modelling with stress distribution at room temperature and 100 K

“…The plastic behaviour of CdHgTe is also not well known. The yield stress has been estimated at 12 MPa by Ballet et al [30] . This value can be impacted by a possible diffusion of the zinc present in the CdZnTe epitaxial substrate to the CdHgTe active layer before thinning.…”

Submicronic Laue diffraction to determine in-depth strain in very closely matched complex HgCdTe/CdZnTe heterostructures with a 10−5 resolution

“…Moreover, the introduction of molecular beam epitaxial (MBE) heterostructures, localized doping, dual-color detection or thermal annealing induces strong in-depth compositional gradients, as well as abrupt interfaces and multiple HgCdTe layers of different Hg/Cd ratio leading to layers that cannot be all matched to the substrate. Even though the lattice mismatch can be limited to very low 10 À4 levels, efficient IR absorption requires a large thickness of HgCdTe which, combined with the low 10-20 MPa elastic limit of HgCdTe (Ballet et al, 2013), may lead to misfit dislocation generation (Yoshikawa, 1988;Matthews & Blakeslee, 1974) and therefore to a rapid degradation of detector general performances (Jó wikowski & Rogalski, 2000;Figgemeier et al, 2003;Johnson et al, 1992). Consequently, characterization of strain in those complex structures requires spatially resolved measurements to be meaningful.…”

“…While strain and plastic relaxation of a single epitaxial HgCdTe layer grown on a CdZnTe substrate have been studied through high-resolution X-ray diffraction (HRXRD) (Ballet et al, 2013;Skauli & Colin, 2001), etch pit density revelation (Fourreau et al, 2016) and surface cross-hatching observation (Tobin et al, 1995;Martinka et al, 2002), there has been no report of in-depth strain measurement. Here, we demonstrate that local diffraction using a submicronic white X-ray beam may provide a cross section of any HgCdTe/ CdZnTe heterostructures with an in-depth spatial resolution of $ 500 nm while still retaining the required resolution of 10 À5 over the strain imposed by the very low lattice mismatch of the HgCdTe/CdZnTe system.…”