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InAs/Ga(1-x)In(x)Sb infrared superlattice diodes. Correlation between surface morphology and electrical performance

InAs/(GaIN)Sb Infrarot-Übergitter-Dioden. Korrelation der Oberflächenmorphologie mit den elektrischen Eigenschaften

Goodnick, S.M. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Materials and electronics for high-speed and infrared detectors
Bellingham, Wash.: SPIE, 1999 (SPIE Proceedings Series 3794)
ISBN: 0-8194-3280-6
pp.41-46 : Ill., Lit.
Conference on Materials for High Speed Detectors <1999, Denver/Colo.>
Conference Paper
Fraunhofer IAF ()
InAs/(GaIn)Sb supperlattices; InAs/(GaIn)Sb Übergitter; infrared photodiode; Infrarot-Photodiode; Oberflächenmorphologie; surface morphology

The structural properties of InAs/Ga(1-x)In(x)Sb infrared (IR) superlattice layers grown by MBE on GaSb substrates have been investigated using high-resolution X-ray diffraction, atomic force microscopy (AFM), secondary ion mass spectroscopy and photoluminescence (PL) spectroscopy. Excellent layers could be grown with a residual mismatch below 1 x 10(exp -3) showing interference oscillations in the X-ray diffraction pattern and high PL efficiency. IR-photodiodes processed from such layers show high responsivity and low leakage currents. The influence of n- and p-doping on the PL efficiency of IR superlattices has been investigated, showing a stronger decrease of the PL intensity for n-doping than for p-doping. Growing the IR-SLs with an As/In V/III ratio below 5, defects with a size of about 1 to 5 mu m in diameter are observed in the AFM scans. The surface morphology between the defects remains perfect. The defects do not significantly affect the X-ray diffraction patterns and the PL intensity. In a minority-carrier-device, such as IR-photodiodes, the defects are associated with defect-assisted tunneling currents leading to a strong degradation of the electrical performance. By optimizing the growth conditions the defect density can be significantly reduced resulting in a surface roughness given by the standard deviation of the measured height profile of the AFM measurement below 0.3 nm leading to excellent device performance.