PV25-1011 – Secondary Ion Mass Spectrometry (SIMS) Standard Test Method for Photovoltaic Application Published
By Kevin Nguyen, SEMI Standards
Evaluation of Photovoltaic (PV) silicon substrate and feedstock allows solar cell manufacturers to control appropriate parameters for improving cell performance. Carbon and oxygen impurities in silicon may form related defects and therefore, degrade the performance of silicon solar cells. Controlling both impurities is absolutely essential to improve cell efficiency.
PV25-1011 - Test Method for Measuring Oxygen, Carbon, Boron and Phosphorus in Solar Silicon Wafers and Feedstock by Secondary Ion Mass Spectrometry was recently published to offer to quantitatively measure the key impurities boron, phosphorus, oxygen and carbon in silicon substrates (thin and thick) and silicon feedstock. Inter-laboratory study is being conducted to study precision of this test method.
Secondary Ion Mass Spectrometry (SIMS) test methods have been around for years and are published in SEMI for measuring impurities, e.g., MF1528 (Boron) and MF1366 (Oxygen). However, there was previously no test method for measuring Carbon and Phosphorus in polished silicon samples. This new standard will complement PV17-0611 Specification for Virgin Silicon Feedstock Materials for Photovoltaic Applications and PV22-1011 Specification for Silicon Wafers for Use as Photovoltaic Solar Cells, which both reference SIMS as a technique for measuring oxygen, carbon, boron and phosphorus in solar silicon wafers and silicon feedstock.
Dick Hockett (Evans Analytical Group), the author, states, “This test can be performed using older, or used SIMS equipment. This test method reduces the cost of controlling and/or qualifying this key material. By standardizing this test method we are offering one “international ruler” for commerce.”
SEMI PV25 was developed by the International PV Analytical Test Methods Task Force (TF), which was formed in fall of 2007. In addition to PV25, the task force completed four other test methods below and is also working on Test Method for the Measurement of Elemental Impurity Concentrations in Silicon Feedstock for Silicon Solar Cells by Bulk Digestion, Inductively Coupled-Plasma Mass Spectrometry.
- SEMI PV1-0211 Test Method for Measuring Trace Elements in Silicon Feedstock for Silicon Solar Cells by High-Mass Resolution Glow Discharge Mass Spectrometry
- SEMI PV9-0611 Test Method for Excess Charge Carrier Decay in PV Silicon Materials by Non-Contact Measurements of Microwave Reflectance After a Short Illumination Pulse
- SEMI PV10-1110 Test Method for Instrumental Neutron Activation Analysis (INAA) of Silicon
- SEMI PV13-1111 Test Method for Contactless Excess-Charge-Carrier Recombination Lifetime Measurement in Silicon Wafers, Ingots, and Bricks Using an Eddy-Current Sensor
How to Get Involved
SEMI Standards Watch, December 2011