AbstractQuantum structures were fabricated by immersing a crystalline silicon (Si) or germanium (Ge) wafer in hydrofluoric acid followed by laser‐induced etching with a laser photon energy of 2.41 eV. Atomic force microscopy (AFM) investigations of Si(100) etched samples reveal a complex surface morphology with pits from the top view and pillar‐like structures from the three‐dimensional view of the pit wall. For Ge(111) laser‐etched samples, AFM shows parallel wall‐type structures and Ge quantum structures on the surface of the walls. Laser‐induced etching of Ge is reported for the first time. Observation of photoluminescence spectra from both samples confirms the presence of quantum confined structures. Line‐shape analysis of Raman spectra is used to estimate the size of the quantum structures. The sizes of nanoparticles can be controlled by the laser power density and irradiation time for etching. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)