InGaPAs-InP double-heterojunction high-radiance LED's

InGaPAs-InP double-heterojunction (DH) high-radiance LED's (λ ∼ 1.05-1.3 µm) have been fabricated by liquid-phase epitaxy (LPE) at constant temperature. The crystal growth procedure is described and the influence of InP substrate crystalline perfection is discussed. LED's with a high-radiance geometry suitable for coupling to an optical fiber have been fabricated. The four-layer double-heterostructure LED's have low forward-biased resistances. Typical external quantum efficiencies of ∼1.5 percent and narrow emission linewidths (∼56 nm, typical), have been measured for LED's (λ ∼ 1.08 µm) with an InGaPAs active layer thickness of 1.6 µm and an active layer carrier concentration of
N_{A} - N_{D} \approx 2.8 \× 10^{16}
cm
^-3
. The dependence of LED emission linewidth upon active layer doping is reported. Transient measurements show that the LED rise time is dependent upon current density for high-injection conditions. Preliminary lifetest results demonstrate only slight LED degradation after operation at 50 and 70°C for times up to ∼3500 h.