A PNPN type negative-resistance laser has been obtained with the following heterojunction. structure.n·GaAs/N·Ga1-xAlxAs/p·GaAs/P·Ga1-yAly As/p·GaAs/n·GaAs/P·Ga1-z AlzAs where x=0.2-0.3

y≤0.20

z≈0.10. The operation mechanism and the process technology of this type of devices are discussed

The condition for "on" turning is analyzed and some electrical parameters and stimulated emission characteristics of the devices are measured. These devices have a turn-on voltage of about 15-20V

and the stand-on current is about 10

1

00mA

while the corresponding stand-on voltage is about 1.5V. The lowest threshold current density is about 2500A/cm2. Stimulated emission by self-oseillations may easily be realized when the device is connected in a simple relaxation circuit.