Germanium cantilever beam type two-dimensional photonic crystal microcavity and preparation method

The invention provides a germanium cantilever beam type two-dimensional photonic crystal microcavity, which comprises a semiconductor substrate with a buried oxide layer and a surface layer which is a cantilever beam type germanium material layer, wherein the germanium material layer comprises a photonic crystal microcavity. The photonic crystal microcavity consists of holes arranged periodicallybut part of area is short of holes. In addition, the invention further provides a preparation method of the germanium cantilever beam type two-dimensional photonic crystal microcavity. The method comprises the following steps: firstly, doping the germanium material layer of the semiconductor substrate with the buried oxide layer and the surface layer which is the cantilever beam type germanium material layer to from a n type heavy doping layer, then performing micromachining to the germanium material layer to form the photonic crystal microcavity, then photoetching and etching the part of area to expose part of the buried oxide layer, and then performing wet erosion to remove the buried oxide layer under the photonic crystal microcavity and release the germanium cantilever beam. The preparation method of invention has the advantages of transforming germanium to a direct band gap by adjusting the strain on the cantilever beam through an external force and improving the light emitting efficiency by means of the photonic crystal microcavity.