Regensburg 2002 – wissenschaftliches Programm
HL 44.4: Vortrag
Freitag, 15. März 2002, 11:30–11:45, H15
THERMAL ANALYSIS FOR CW-OPERATION OF InGaN LASER DIODES — •V. Kümmler, G. Brüderl, S. Bader, S. Miller, A. Weimar, A. Lell, and V. Härle — OSRAM Opto Semiconductors, Wernerwerkstraße 2, Regensburg, GERMANY
OSRAM OS is developing InGaN/GaN-MQW-laser diodes with lowest threshold currents at wavelengths around λ = 400 − 420 nm for use in high density data storage and laser printing. N-Conducting SiC is used as substrate, which makes edge emitting lasers with a vertical current path and cleaved and coated mirror facettes possible. These devices show threshold current densities of jth = 6.3 kA/cm2 and voltages of Uth = 12,5 V. The bare diode bar is lasing in CW without heat sinking. Lifetimes can be significantly enhanced by mounting the device on a heat sink with either p-side up or down bonding. The lifetime is highly dependent on the temperature profile during operation. We have investigated the lasing behavior for similar diodes on different heat sinks and with p-side up or down mounting. P-side down mounted diodes on a heat sink have shown 2 minutes of CW-lasing (T = 25 ∘C) at 1 mW optical power while only 25 seconds were possible with non mounted laser bars. Lasers with 600 µ m resonator length showed better cw-lasing than those with shorter resonators. These lasers had nearly identical threshold current densities jth, but are not as efficient in heat transfer to the sink. These experimental measurements are explained using a thermal conduction model.