Characteristics of InGaAsP/InP p-DCC lasers grown by the three-melt technique

Long wavelength (
1.3-1.55 \mu
m) diode lasers have exhibited an undesirably sensitive temperature dependence of threshold current, the so-called T
0
problem. Several mechanisms have been investigated as the source of this behavior, including carrier leakage and Auger recombination. We propose and demonstrate a new device, the p-DCC laser, which is grown by a three-melt LPE technique on p-type substrates. This diode exhibits a low threshold (
Jth = 2.6
kA/cm
²
for broad area devices) and high T
0
(180 K) since the p-DCC structure provides improved carrier confinement and cooling of hot carriers. Thresholds as low as 2.0 kA/cm
²
have been observed for devices with thin (∼ 500 Å) active and separation layers, but the T
0
has decreased to 106 K. It is evident that the p-DCC structure provides a device which is superior to a conventional DHL with a thicker active layer. We conjecture that leaky electrons, possibly generated by Auger recombination, are efficiently cooled by scattering processes as they diffuse through the separation layer and into the second active layer where they radiatively recombine. The devices have been modeled using the Purdue University Program for Heterostructure Simulation (PUPHS), and an attempt has been made to optimize the device parameters in order to attain low threshold, high T
0
lasers.