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InN quantum dots (QDs) were grown on Si (111) by epitaxial Stranski-Krastanow growth mode using plasma-assisted molecular beam epitaxy. Single-crystalline wurtzite structure of InN QDs was verified by the x-ray diffraction and transmission electron microscopy. Scanning tunneling microscopy has been used to probe the structural aspects of QDs. A surface bandgap of InN QDs was estimated from scanning tunneling spectroscopy (STS) I-V curves and found that it is strongly dependent on the size of QDs. The observed size-dependent STS bandgap energy shifts with diameter and height were theoretical explained based on an effective mass approximation with finite-depth square-well potential model. [ABSTRACT FROM AUTHOR]

In this work, we report enhanced power conversion efficiency (PCE) of bulk heterojunction polymer solar cells by Förster resonance energy transfer (FRET) from samarium-doped luminescent gadolinium orthovanadate (GdVO4:Sm3+) quantum dots (QDs) to polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) polymer. The photoluminescence emission spectrum of GdVO4:Sm3+ QDs overlaps with the absorption spectrum of PTB7, leading to FRET from GdVO4:Sm3+ to PTB7, and significant enhancements in the charge-carrier density of excited and polaronic states of PTB7 are observed. This was confirmed by means of femtosecond transient absorption spectroscopy. The FRET from GdVO4:Sm3+ QDs to PTB7 led to a remarkable increase in the power conversion efficiency (PCE) of PTB7:GdVO4:Sm3+:PC71BM ([6,6]-phenyl-C71-butyric acid methyl ester) polymer solar cells. The PCE in optimized ternary blend PTB7:GdVO4:Sm3+:PC71BM (1:0.1:1.5) is increased to 8.8% from 7.2% in PTB7:PC71BM. This work demonstrates the potential of rare-earth based luminescent QDs in enhancing the PCE of polymer solar cells. [ABSTRACT FROM AUTHOR]

InN quantum dots (QDs) were fabricated on silicon nitride/Si (111) substrate by droplet epitaxy. Single-crystalline structure of InN QDs was verified by transmission electron microscopy, and the chemical bonding configurations of InN QDs were examined by x-ray photoelectron spectroscopy. Photoluminescence measurement shows a slight blue shift compared to the bulk InN, arising from size dependent quantum confinement effect. The interdigitated electrode pattern was created and current-voltage (I-V) characteristics of InN QDs were studied in a metal-semiconductor-metal configuration in the temperature range of 80-300 K. The I-V characteristics of lateral grown InN QDs were explained by using the trap model. [ABSTRACT FROM AUTHOR]

The present work explores the temperature dependent transport behavior of n-InN nanodot/p-Si(100) heterojunction diodes. InN nanodot (ND) structures were grown on a 20 nm InN buffer layer on p-Si(100) substrates. These dots were found to be single crystalline and grown along [001] direction. The junction between these two materials exhibits a strong rectifying behavior at low temperatures. The average barrier height (BH) was determined to be 0.7 eV from current-voltage-temperature, capacitance-voltage, and flat band considerations. The band offsets derived from built-in potential were found to be ΔEC=1.8 eV and ΔEV=1.3 eV and are in close agreement with Anderson's model. [ABSTRACT FROM AUTHOR]