Method of laser treatment of a semiconductor wafer comprising AlGaInP-LEDs to increase their light generating efficiency

A method for treating a semiconductor wafer comprising a set of aluminum gallium indium phosphide light emitting diodes (AlGaInP-LEDs), wherein each AlGaInP-LED includes a core active layer for light generation sandwiched between two outer layers, the core active layer having a central light generating area and a peripheral edge surrounding the central light generating area, the method comprising:

• treating, by a laser beam treatment, the peripheral edge of the core active layer of each AlGaInP-LED with a laser beam thereby increasing a minimum band gap in each peripheral edge to such an extent that, during operation of the AlGaInP-LED, an electron-hole recombination is essentially confined to the central light generating area;
• and
• after the laser beam treatment, mesa etching the wafer thereby obtaining, for each AlGaInP-LED, a chip preform, wherein each chip preform comprises a central zone and a laser beam treated peripheral boundary,
• wherein a photon energy of the laser beam is higher than the minimum band gap of the core active layer and lower than band gaps of the two outer layers such that, during the laser beam treatment, a laser beam energy is primarily transferred to the peripheral edge of the core active layer.