(Opto)Electrical Characterization of III-V Semiconductor Nanowires Using SPM Techniques
(2014) FYSM60 20141Department of Physics
Synchrotron Radiation Research
- Abstract
- This study presents structural and electrical properties of individual, upright standing III-V semiconductor nanowires obtained by scanning probe microscopy (SPM). The work is divided in two major parts. First, we report on optoelectrical characterization of individual InP nanowires in their free standing geometry utilizing scanning tunneling microscopy (STM). We present measured current-voltage (I-V ) characteristics before and after sample processing under atomic hydrogen. We present the output parameters: open circuit voltage Voc, short circuit current Isc, as well as ideality factor as a function of surface treatment. Secondly, we utilize atomic force microscopy (AFM) in static and amplitude modulated-AFM and characterize In0.1Ga0.9N... (More)
- This study presents structural and electrical properties of individual, upright standing III-V semiconductor nanowires obtained by scanning probe microscopy (SPM). The work is divided in two major parts. First, we report on optoelectrical characterization of individual InP nanowires in their free standing geometry utilizing scanning tunneling microscopy (STM). We present measured current-voltage (I-V ) characteristics before and after sample processing under atomic hydrogen. We present the output parameters: open circuit voltage Voc, short circuit current Isc, as well as ideality factor as a function of surface treatment. Secondly, we utilize atomic force microscopy (AFM) in static and amplitude modulated-AFM and characterize In0.1Ga0.9N truncated nanopyramids. By applying conductive AFM (C-AFM), we can correlate structural and electronic properties of the nanopyramids. For this, two-dimensional current images are recorded simultaneously with topography images and local I-V measurements are obtained. Local current voltage characteristics exhibit Schottky like behavior at small forces and a strong increase of the current at higher tip loading forces. We measure the Schottky barrier height and observe that the piezoelectric properties of the InGaN nanopyramids upon mechanical stress from the AFM tip significantly reduce the Schottky barrier height. (Less)
- Popular Abstract
- Characterization of nanowire based devices
In the late 80's a mobile phone was a heavy piece worn in a handle and the world-wide-web was introduced. Since then the miniaturization has made phones a 0.15 kg computers, and it has brought about nano devices to make more efficient, long lifetime, low-cost solar cells and light emitting diodes (LEDs). These nano devices are interesting to a general public due to all their applications. However, as quantum systems they are also interesting scientific objects. This work is devoted to a specific quantum object: nanowires (NWs), which are anysotropic structures with a diameter of a few nanometer (nm). To put this scale in perspective it is worth mentioning that a human hair is on the order of... (More) - Characterization of nanowire based devices
In the late 80's a mobile phone was a heavy piece worn in a handle and the world-wide-web was introduced. Since then the miniaturization has made phones a 0.15 kg computers, and it has brought about nano devices to make more efficient, long lifetime, low-cost solar cells and light emitting diodes (LEDs). These nano devices are interesting to a general public due to all their applications. However, as quantum systems they are also interesting scientific objects. This work is devoted to a specific quantum object: nanowires (NWs), which are anysotropic structures with a diameter of a few nanometer (nm). To put this scale in perspective it is worth mentioning that a human hair is on the order of 50,000 to 100,000 nm in diameter.
In this study we utilize two microscopes: scanning tunneling microscope (STM) and atomic force microscope (AFM) in order to both image and measure electrical characteristics of individual nanowires. Since the microscopes utilize scanning tip, which makes a point contact with the top of a nanowire, this allows to image and probe interactions between the tip and the sample.
Electrical measurements of Indium Phospate, InP, nanowire solar cell have been reported utilizing STM in dark whereas a response to light of nanowire solar cell has been studied with a laser diode. Study of the photo-generated current was measured for five NWs, revealing that for efficient nanowire based solar cells, the passivation of the nanowire surface is essential.
Investigation of the topography of Indium Galium Nitrade, InGaN, nanowires is provided using AFM. Utilizing conductive- AFM we observe that surface conductivity varies due to the change in the In concentration. Furthermore, we show that it is possible to generate electrical current when the stress is applied to the nanowire. This implies that the nanowire could act as a nanogenerator, harnessing mechanical energy to power up small devices.
Such a study, where we investigate the individual nanowires electrical properties, will allow in the future to improve the entire device performance making better LEDs and solar cells. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/4690402
- author
- Colvin, Jovana LU
- supervisor
-
- Rainer Timm LU
- organization
- course
- FYSM60 20141
- year
- 2014
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Semiconductor nanowire, scanning tunneling microscopy, atomic force microscopy, conductive atomic force microscopy, Ohmic contact, Schottky contact, Schottky barrier height, Piezoelectricity
- language
- English
- id
- 4690402
- date added to LUP
- 2014-12-16 14:59:15
- date last changed
- 2014-12-16 14:59:15
@misc{4690402,
abstract = {{This study presents structural and electrical properties of individual, upright standing III-V semiconductor nanowires obtained by scanning probe microscopy (SPM). The work is divided in two major parts. First, we report on optoelectrical characterization of individual InP nanowires in their free standing geometry utilizing scanning tunneling microscopy (STM). We present measured current-voltage (I-V ) characteristics before and after sample processing under atomic hydrogen. We present the output parameters: open circuit voltage Voc, short circuit current Isc, as well as ideality factor as a function of surface treatment. Secondly, we utilize atomic force microscopy (AFM) in static and amplitude modulated-AFM and characterize In0.1Ga0.9N truncated nanopyramids. By applying conductive AFM (C-AFM), we can correlate structural and electronic properties of the nanopyramids. For this, two-dimensional current images are recorded simultaneously with topography images and local I-V measurements are obtained. Local current voltage characteristics exhibit Schottky like behavior at small forces and a strong increase of the current at higher tip loading forces. We measure the Schottky barrier height and observe that the piezoelectric properties of the InGaN nanopyramids upon mechanical stress from the AFM tip significantly reduce the Schottky barrier height.}},
author = {{Colvin, Jovana}},
language = {{eng}},
note = {{Student Paper}},
title = {{(Opto)Electrical Characterization of III-V Semiconductor Nanowires Using SPM Techniques}},
year = {{2014}},
}