Nanocrystal array, laser device, and display device

A display device comprising:

• a casing;
• and
• a laser device located in the casing, the laser device comprising:
• a substrate comprising a first surface and a second surface opposite to the first surface, the first surface being recessed toward the second surface to form at least one hole;
• a drain electrode formed in each of the at least one hole;
• a nanocrystal array located on the drain electrode, the nanocrystal array comprising a plurality of nanorods arranged in an array, each of the plurality of nanorods comprising a nanorod buffer layer, a first type semiconductor layer, a tunnel junction layer, a second type semiconductor layer, a multi-quantum well, and another first type semiconductor layer successively stacked on each other;
• a conductive layer located on the nanocrystal array;
• and
• an electrode layer located on the conductive layer;
• wherein the substrate comprises a silicon substrate, a first insulation layer, and a semiconductor layer successively stacked on each other;
• the silicon substrate has a main surface with (100) crystal plane, the first insulation layer is located on the main surface, a surface of the semiconductor layer away from the first insulation layer is defined as the first surface, and a surface of the silicon substrate away from the first insulation layer is defined as the second surface;
• the at least one hole penetrates through the semiconductor layer and extends into the silicon substrate, each of the at least one hole defines a sidewall and a bottom surface connected to the sidewall, the bottom surface is inclined with the silicon substrate, and a (111) crystal plane of the silicon substrate is exposed from the bottom surface.