InGaN/GaN

Nakamura S, Senoh M, Nagahama S, Iwasa N, Matsushita I and Mukai T 1999 InGaN/GaN/AIGaN-based LEDs and laser diodes MRS Internet J. Nitride Semicond. Res. 4S1 G1.1... 

The crystal quality of the InGaN QWs becomes poor mainly due to the lattice-constant mismatch and the difference of the thermal expansion coefficient between InN and GaN with increasing the In composition [4,5]. Therefore, in order to improve the external quantum efficiency (i/ext) of the InGaN-based LEDs and LDs, it is important to elucidate and optimize the effects of the various growth conditions for the InGaN active layer on the structural and optical properties. Recently, we reported a fabrication of efficient blue LEDs with InGaN/GaN triangular shaped QWs and obtained a substantial improvement of electrical and optical properties of the devices [6,7]. 

Fig. 2. High resolution XRD patterns of InGaN/ GaN MQW as a function of flow rate of TMIn.

Effect of plasma-induced damage on electrical properties of InGaN/GaN multiple quantum well light-emitting diodes... 

Fig. 3. Forward (top) and reverse (bottom) voltages of InGaN/GaN MQW LED with and without annealing after etching as a function of ICP source power.

Carrier and exciton dynamics in InGaN/GaN MQWs have also been studied at a high optical pumping power [34], At 7 K, a radiative decay lifetime of 250 ps was observed for the dominant transition at a generated carrier density of 1012/cm2. The time-resolved measurement showed that the decay of PL has a bimolecular recombination characteristic. At room temperature, the carrier recombination was found to be dominated by non-radiative processes with a measured lifetime of 130 ps. Well width dependence of carrier and exciton dynamics in InGaN/GaN MQWs has also been measured [35]. The dominant radiative recombination at room temperature was attributed to the band-to-band transition. Combined with an absolute internal quantum efficiency measurement, a lower limit of 4 x 10 9 cm3/s on the bimolecular radiative recombination coefficient B was obtained. At low temperatures, the carrier... 

A phenomenon which is related to the PPC effects is the optical metastability in GaN. Optical metastability has been observed in GaN epilayers and InGaN/GaN multiple quantum wells [24-26]. Optical metastability in bulk GaN was manifested by a photoinduced decrease in the output intensity of the bandedge transition at 365 nm followed by an increase in the output intensity of a new emission band at 378 nm [25], The recovery time associated with the observed optical metastability is very long (weeks). The cause for such an effect was attributed to the presence of traps in bulk GaN [25], In... 

FIGURE 6 Electroluminescence of InGaN/GaN and AlGaN/GaN double heterostructure LEDs grown by PMBE [70] and RMBE [27], respectively. 

C5.1 InGaN/GaN/AlGaN-based laser diodes C5.2 Optically pumped lasing and current injection lasing in GaN-based laser structures... 

C5.5 InGaN/GaN laser diodes grown on 6H-SiC C5.6 Technologies for GaN surface emitting lasers C5.7 Role of defects in GaN-based lasers C5.8 GaN-based UV detectors... 

Thus, great progress has been achieved in III-V nitride-based LEDs and LDs recently. Here, the present status of InGaN/GaN/AlGaN-based LDs is described considering the behaviour of TDs. 

C STRUCTURE OF InGaN/GaN/AIGaN-BASED LASER DIODES... 

High-temperature SE was also observed in MOCVD-grown InGaN/GaN MQWs up to 575 K [23], The number of periods of the MQWs was 12, the nominal well and barrier layer thicknesses were 30 and 45 A,... 

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