Solar Power Program Clara Paola Murcia S.

BS in Electrical Engineering (Universidad de Los Andes)Concentration in Power Systems / Minor in BA

Semiconductor processing skills: - Photolithography- Automated wafer dicing (and manual scribing)- Wet and dry etching (isotropic, anisotropic) of silicon and dielectric materials- E-beam and thermal material deposition- Standard semiconductor cleaning processes- Phosphorous diffusion (POCl 3)- Wet and dry thermal oxide growth- Reactive ion etching (RIE)- Rapid thermal processing (RTP)- Wire bonding. - Knowledgeable with safety systems, procedures and regulations. Device testing and characterization skills:- Sheet resistance testing with four point probe- Current-voltage characterization of fundamental devices- Carrier lifetime and voltage measurement with quasi-steady state photoconductance (QSSPC) decay- Scanning electron microscopy (SEM)- Outdoor testing of photovoltaic cells- 3D interference microscopy (Zygo)- External quantum efficiency (EQE)- Thin film characterization with spectroscopical ellipsometry (UVISEL)- Low temperature (77K and 4K) testing of emitting devices using Fourier transform infrared spectroscopy (FTIR )

Background and Skills

Solar Power Program

Lack of emitters in the THz regime. Previous results reported edge

emission. Top emitters are easily integrated to other optoelectronic

devices

THz emission from p-doped Si (MS)Motivation

New sources and materials need to be developed and characterized in

the “terahertz gap” 3 to 30

Solar Power Program

• IQE is applied to measure critical thin Si solar cell parameters

• Design rules for high performance developed and demonstrated

Best Parameters (18um solar cell):

• Voc: 631mV• Jsc (1 pass): 22mA/cm2

• FF:81.7%

Thin silicon solar cells can be higher efficiency than thick silicon with the same materials

properties due to reduced bulk recombination that leads to higher voltages

Thin Silicon Solar Cells

High Performance Thin Si Solar Cells (PhD)

Reduced bulk volume (Reduced Recombination)•Light Trapping•Low front and back surface recombination

High Open Circuit Voltage

High Efficiency

PhD Students C. Paola Murcia and Ruiying Hao. Epitaxial layers grown by collaborative research with AmberWave Inc.

Thin Silicon Solar Cell Results

Planar Thin Silicon Solar Cells

Contact -Reflector

Solar Cell

PassivationLight Trapping

Ideal Thin Si Solar Cell

• A high performance thin silicon solar cell is based on a high open circuit voltage design .

• The light trapping consists of a back surface and reflector that can be independently optimized and a front surface texture and ARC

• The thin Si solar cell is grown on high quality material then transferred to a holding substrate.

X SEM of 18um thin Si solar cell

QE before ARC