An apparatus comprises a first electrical contact, a second electrical contact, and a semiconductor device disposed between the first and second electrical contacts. The semiconductor device comprises a laser diode and a temperature control unit. The laser diode comprises p-type semiconductor material and n-type semiconductor material. The temperature control unit comprises p-type semiconductor material, n-type semiconductor material, and a resistor coupled to the laser diode. One of the p-type semiconductor material and the n-type semiconductor material is shared by the laser diode and the temperature control unit.