Thermoelectric conversion requires materials with low thermal conductivity k high electrical conductivity s and thermopower P. Performance of thermoelectric material is evaluated by the zT=P^2sT/k figure-of-merit. Bi2Te3 or Sb2Te3 are usually used near room temperature but they are harmful, expensive and incompatible with CMOS technologies, as opposed to Silicon Si, Germanium Ge or Silicon-Germanium SiGe. Although Si and Ge feature high P and s, their usage in thermoelectricity is hindered by their high k that lowers zT. Modern nanotechnology offers the opportunity to reduce k by altering the phonon band structure using 2D structures. In this paper, a particular emphasis is put on the use of suspended Si and SiGe thin-films to reduce k. To study the dramatic reduction of k in thin-film membranes, an integrated measurement platform has been designed and fabricated. This platform consists in two metallic serpentines directly integrated on the membranes, one acts as a heater and the second as a sensor. Under condition that convection losses can be neglected, the measured temperature difference across the membrane, the Joule power released in the heater and the membrane dimensions are used to determine k.For a 60nm thick Si thin-film, a k value around 50W/m/K was obtained which is 3× smaller compared to bulk.This paper discusses the advantages of using Si and SiGe thin-films to elevate CMOS compatible materials as competitive contenders compared to e.g. telluride-based compounds.