Intersubband photonic devices by group-III nitrides

• The characteristics of intersubband transitions in III-nitride quantum wells are promising for detectors and all-optical switches through a high intrinsic speed (similar to 1 THz), and can also provide a high optical saturation power and a desired small negative chirp parameter in electroabsorption modulators. The high LO-phonon energy allows to improve the operating temperature of THz emitters. Recent achievements and prospects for intersubband III-nitride photonic devices, mainly for lambda=1.55 mu m, are briefly reviewed. Further, means to enhance material quality by achieving crack-free growth of GaN/AlN multiple-quantum-well (MQW) structures, and by employing intersubband transitions in multiple-quantum-disk (MQD) structures incorporated into dislocation free GaN nanocolumns are discussed. We investigate the occurrence of cracks in MBE-grown GaN/AlN MQWs on GaN MOVPE templates with respect to the buffer layer, the number of QWs and the temperature reduction rate after growth. Intersubband absorption in GaN/AlN MQDs in the wavelength range 1.38-1.72 mu m is demonstrated in three samples grown on Si(111).

Nyckelord

intersubband transition

electroabsorption modulator

quantum well infrared photodetector (QWIP)

alloptical switch

quantum cascade laser

GaN

AlN

GaN template

nanocolumn

molecular beam epitaxy

TECHNOLOGY

TEKNIKVETENSKAP

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