GB1378128A - Semiconductor laser - Google Patents

Abstract

1378128 Electroluminescence Z I ALFEROV V M ANDREEV V I KOROLKOV V G NIKITIN G T PAK A I PETROV E L PORTNOI and V I SHVEIKIN 26 June 1973 30291/73 Heading C4S [Also in Division H1] A semi-conductor laser with negative resistance characteristics to excitation current comprises a five-layer heterostructure, Fig. 1, of which adjacent layers 1 to 4 are of opposite conductivity type, layer 4 is a light-emitting layer, and an outer layer 5 is of the same conductivity type as the adjacent light-emitting layer 4. The forbidden zone of the lightemitting layer should be of lesser width than the forbidden zones of layers 3 and 5, and a resonator for the layer 4 is formed by cut reflective end surfaces 10, 11. The laser may form part of a self pulsing excitation circuit comprising a D.C. supply connected to a capacitor charging circuit R, C, the laser being pulse excited each time the condenser voltage reaches the negative resistance threshold, layers 1 and 2 are respectively N and P doped and may consist of Al x1,2 Ga 1-x1,2 As, where x 1,2 is a valuebetween 0 and 0À5, while layer 3 may consist of N-type Al x2 GA 1-x3 As with x 3 between 0À05 and 0À5. The light-emitting layer 4 is made of P- type Al x4 Ga 1-x4 As, where x 4 is a value between 0 and 0À37, while layer 5 is of P-type AP x5 Ga 1-x5 As with x 5 between 0À05 and 0À5. The required relationship between forbidden zone widths is satisfied by the relationship x 3 #x 5 >x 4 . A value of x 3 between 0 and 0À27 produces radiation selectively over the range from visible red to infra-red at room temperature. The semiconductor crystal is manufactured by liquid or vapour phase epitaxial growth on a GaAs substrate, and optionally may be formed of indium arsenide, indium phosphide, indium arsenide-gallium arsenide or indium phosphidegallium phosphide.