This book provides new research on polycrystalline films. Chapter One reviews the characterisation of polycrystalline Cu2ZnSn(SxSe1-x)4 thin-films and solar-cells. Chapter Two explains the chemical vapor deposition process accelerated by the fragments of monomethylsilane. Chapter Three studies the regularities of formation of the nanostructured films of polycrystalline silicon doped with germanium as isovalent impurity.