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Electronic and photoconductive properties of ultrathin InGaN photodetectors

Elektronisch und photoleitende Eigenschaften von ultradünnen InGaN Photodetektoren
: Lebedev, V.; Polyakov, V.M.; Hauguth-Frank, S.; Cimalla, V.; Wang, C.-Y.; Ecke, G.; Schwierz, F.; Schober, A.; Lozano, J.G.; Morales, F.M.; Gonzales, D.; Ambacher, O.


Journal of applied physics 103 (2008), Nr.7, Art. 073715, 7 S.
ISSN: 0021-8979
ISSN: 1089-7550
Fraunhofer IAF ()
InGaN; optoelectronic property; optoelektronische Eigenschaft; Photodetektor; photodetector

We report on the compositional dependencies of electron transport and photoconductive properties for ultrathin metal-semiconductor-metal photodetectors based on In-rich In(x)Ga(1-x)N alloys. For a In0.64Ga0.36N/GaN structure, the rise time close to the RC constant at low fields has been measured along with a transparency of about 77% and an absorbance of about 0.2 at a wavelength of 632 nm. The electron density profiles and low-field mobilities for different compositions of InGaN have been calculated by numerically solving the Schrödinger and Poisson equations and applying the ensemble Monte Carlo method, respectively. It was demonstrated that in ultrathin In(x)Ga(1-x)N/GaN (0.5 < x <1) heterostructures, in contrast to bulk InN exhibiting a strong surface electron accumulation, free electrons mostly tend to accumulate at the buried InGaN/GaN interface. We have also found that the low-field mobility in the InGaN/GaN heterostructures is strongly limited by the buried interface roughness which causes more than 95% of all scattering events occurred by two-dimensional electron transport under low electric field conditions.