Halvard Haug

Institute for Energy Technology | IFE · Department for Solar Energy

In this paper we use temperature- and injection dependent lifetime spectroscopy (TIDLS) to identify the energy levels Et and capture cross section ratios k of the main limiting recombination centers in p-type high performance multicrystalline silicon (HPMC-Si) wafers used for solar cell production. To increase the accuracy and applicability of the...

In this work we demonstrate the angular color stability of textured c-Si substrates colored by single layer thin film coatings of SiN x. These coatings show higher angular color stability on substrates with a random upright pyramidal surface texture compared to identical coatings on planar silicon substrates. Angle dependent reflectance measurement...

Due to the fast growth in global installed photovoltaic (PV) capacity, performance monitoring for large-scale PV systems is an increasingly relevant and important topic. A large volume of research exists in this field, but there is a need for comparison of different methods and their performance toward relevant metrics, a broad discussion of the di...

Accurate performance modeling of utility-scale PV plants is crucial for reducing the risk of investment, as well as improving operations and maintenance. In spite of much research, the precise rate at which PV plants degrade is still not well known. This article uses a well-known methodology for calculating degradation rates to assess the impact of...

Methods for quick and accurate detection and diagnosis of defects in PV systems are increasingly important as the global photovoltaic (PV) capacity continues to grow at a rapid pace. Two of the most used methods for defect detection involve aerial infrared thermography and data analysis of production data. In this work, we combine the two methods t...

In many parts of the world, soiling is a significant loss mechanism for PV energy production. Methods for accurately quantifying historical and current soiling losses are needed. Furthermore, state-of-the-art methods to estimate degradation rates based on production data do not handle soiling in a satisfactory manner. In order to accurately estimat...

Reliable monitoring of PV systems is essential to establish efficient maintenance routines that minimize the levelized cost of electricity. The existing solutions for affordable monitoring of commercial PV systems are however inadequate for climates where snow and highly varying weather result in unstable performance metrics. The aim of this work i...

Hydrogen (H) is thought to be strongly involved in the light and elevated temperature-induced degradation observed predominantly in p-type silicon wafers, but the nature of the defect or defects involved in this process is currently unknown. We have used infrared (IR) spectroscopy to detect the vibrational signatures due to the H–B, H–Ga, and H2*(C...

(In spite of the broad title, the main contribution of this paper is a quantitative method for finding optimal data filters for the purpose of string level monitoring.) Due to the rapid growth in the size and number of photovoltaic (PV) power plants, monitoring solutions that ensure a high, reliable power output and low maintenance costs are of i...

In this paper we perform a thorough investigation of the temperature coefficients of c-Si solar cells and wafers, based on both experimental data and device simulations. Groups of neighboring wafers were selected from different heights of four high performance multicrystalline silicon ingots cast using different dopants concentrations and Si feedst...

In this paper we have used a sequential measurement routine to separate and evaluate the effects of two dominant mechanisms for degradation of the carrier lifetime of silicon wafers: Boron-oxygen related light induced degradation (BO-LID) and light and elevated temperature induced degradation (LeTID). Wafers from different heights in a high perform...

This work demonstrates a novel technique for calibrating temperature dependent photoluminescence (PL) images of silicon wafers with high accuracy. The PL signal is calibrated using a heat-controlled photoconductance (PC) stage integrated into the PL imaging system. The PC signal is measured in true steady state condition and used to determine the c...

As the deployment rate of PV power plants continues to soar, the need for robust, scalable methods for performance analytics increases. In this paper, we demonstrate the usefulness of one approach for quantifying soiling rates in utility-scale PV power plants endogenously, i.e., directly from the production data. The temperature corrected performan...

Material híbrido orgánico-inorgánico y método para pasivación de superficie de silicio. Un importante reto tecnológico es la pasivación de la superficie del silicio en dispositivos optoelectrónicos, como las células solares, sin añadir costes adicionales y empleando materiales abundantes. En la presente invención, se propone un método para fabricar...

In this paper, we investigate three different passivating films for use in predictable quantum efficient detectors: two monolayer films of SiNx with different compositions and one double-layer stack of SiNxOy capped with SiNx, all deposited on very high resistivity silicon substrates. In addition to the conventional characterization methods, we als...

Correlations between defect-related luminescence (DRL) and recombination mechanisms of multicrystalline silicon wafers are investigated by hyperspectral photoluminescence (PL) imaging at cryogenic temperatures (∼80 K) and by PL-based techniques for charge carrier lifetime at room temperature. This unique combination of measurement techniques is use...

The minority carrier lifetime is a crucial material parameter in silicon (Si) wafers for use in solar cell applications, and precise measurements of carrier lifetime as a function of the excess carrier concentration (injection level) is of high importance. In this paper we present a method for extracting injection-dependent lifetime data with high...

Three ingots with different doping concentrations have been produced using Elkem Solar Silicon feedstock. Gallium dopants are added to the compensated Elkem Solar Silicon ingots in order to obtain a more uniform resistivity profile throughout the heights, and to avoid a change from p-type to n-type silicon towards the top of the ingots. In addition...

Silicon solar modules typically operate at a higher temperature than the 25 °C used for standard testing, and the temperature coefficient (TC) therefore might have a significant impact on the field performance. In this paper the temperature dependent behavior of compensated Si solar cells has been simulated using PC1Dmod6.2, using a combination of...

Amorphous hydrogenated silicon (a-Si:H) is an important material for surface defect passivation of photovoltaic silicon (Si) wafers in order to reduce their recombination losses. The material is, however, unstable with regard to hydrogen (H) desorption at elevated temperatures, which can be an issue during processing and device manufacturing. In th...

In this paper, we present a study of the silicon surface passivation based on the use of spin coated hybrid composite layers. We investigate both undoped poly(3,4-ethylenedioxythiophene)/poly-(styrenesulfonate) (PEDOT:PSS), as well as PEDOT:PSS functionalized with semiconducting oxide nanomaterials (TiO2 and SnO2). The hybrid compound was deposited...

In this paper we present a novel method for measuring temperature dependent lifetime images with high spatial resolution using photoconductance calibrated photoluminescence (PL) imaging. In order to achieve this, PL images are recorded at various temperatures by implementing a temperature stage into a commercial, steady state PL imaging setup. Carr...

We present a method for extracting local recombination rates from photoluminescence images of double side passivated wafers, using simulations of lateral charge carrier diffusion in two dimensions. By fitting the simulated carrier lifetime map with a calibrated photoluminescence image, the recombination profiles in bulk and at grain boundaries (GBs...

The temporal stability of single layer thin films of hydrogenated amorphous silicon (a-Si:H) and silicon nitride (a-SiNx:H) passivated crystalline silicon wafers have been investigated over 18 months. The thin films were deposited at low temperature with plasma-enhanced chemical vapor deposition (PECVD) onto different substrates, including float zo...

Gallium (Ga) doped silicon (Si) is becoming a relevant player in solar cell manufacturing thanks to its demonstrated low light-induced degradation, yet little is known about Ga-related recombination centers. In this paper, we study iron (Fe)-related recombination centers in as-grown, high quality, directionally solidified, monocrystalline Ga-doped...

We report results from a national project about impurities in high performance multicrystalline silicon: Contamination sources, transport routes, interaction with crystal defects and impact on solar cell efficiency parameters. Several ingots were produced in a lab scale furnace. Growth parameters and crucible types were varied, and high purity quar...

A relevant technological challenge is the low cost and abundant materials developement for silicon surface passivation for applications in optoelectronic devices, in particular in solar cells by scalable industrial methods. In the present invention, a new hybrid material comprising PEDOT:PSS and transparent conducting oxide nanostructures is develo...

Presents corrections to the paper, "Surface passivation properties of HfO2 thin film on n-type crystalline Si,” (Chengetal, X.), IEEE J. Photovolt., vol. 7, no. 2, pp. 479–485, Mar. 2017.

Atomic layer deposited hafnium oxide is shown to provide good surface passivation of low resistivity, n-type crystalline Si wafers after a low temperature anneal. The surface passivation is related to a fixed negative charge, as well as an excellent interface with the crystalline Si wafer. In this paper, the influence of four deposition parameters...

Research on silicon-based tandem heterojunction solar cells (STHSC) incorporating metal oxides is one of the main directions for development of high-efficiency solar cells. In this work, the optical characteristics of a STHSC consisting of a ZnO/Cu2O subcell on top of a silicon-based subcell were studied by optical modelling. Cu2O is a direct-gap p...

The influence of phosphorus diffusion gettering on recombination at grain boundaries has been studied in a commercially cast high performance multicrystalline silicon block. Wafers from four different heights have been studied with high resolution photoluminescence-imaging. The recombination at grain boundaries was studied from linescans perpendicu...

Surface passivation by double layers made of hydrogenated amorphous silicon (a-Si:H) and hydrogenated silicon nitride (SiNx) on float zone n-type Si substrates was investigated. The thickness of the a-Si:H layers was varied from 0 to 4 nm and they were deposited at low temperature by plasma-enhanced chemical vapour deposition. The structure and com...

In this paper we present a new update to PC1Dmod, which extends the original PC1D program by implementing Fermi-Dirac statistics and a range of state-of-the-art models in order to improve the accuracy of c-Si device simulation. In PC1Dmod 6.2 the list of models is further expanded to include a parameterization of incomplete ionization of dopants (A...

In this paper we present a novel approach to investigate the influence of non-uniformity in the minority carrier lifetime of c-Si wafers on solar cell efficiency. By using a combination of one-dimensional device modelling (cmd-PC1D 6) and finite element circuit modelling (Griddler 2) we are able to simulate the total IV characteristics of a solar c...

The surface passivation quality of plasma-enhanced chemical vapor-deposited silicon oxynitride/silicon nitride (a-SiO xN y:H/SiN x) stacks has been investigated for p-type float-zone crystalline silicon wafers. The effective lifetime τeff, density of fixed charge Qf, and density of interface defects Dit were measured as a function of the a-SiO xN y...

A thin SiOyNx film was inserted below a conventional SiNx antireflection coating used in c-Si solar cells in order to improve the surface passivation and the solar cell's resistance to potential-induced degradation (PID). The effect of varying the flow ratio of the N2O and SiH4 precursors and the deposition temperature for the SiOyNx thin film upon...

In this work we show that the high minority carrier lifetime in as-grown Ga-Si wafers is dominated by low levels of iron contamination incorporated during silicon growth. Upon phosphorous diffusion iron is however effectively removed, increasing the bulk carrier lifetime from a few hundred micro-seconds to well above one millisecond. Lifetime spect...

In this work, the recently proposed band-gap narrowing model by Yan and Cuevas [J. Appl. Phys. 114, 044508 (2013)] is evaluated by simulations of the recombination pre-factor J0 of highly phosphorus doped, passivated crystalline silicon surfaces, which are particularly relevant for solar cell applications. The results were fitted to experimental J0...

We investigate the surface recombination velocity Sp at the silicon-dielectric interface of phosphorus-doped surfaces for two industrially relevant passivation schemes for crystalline silicon solar cells. A broad range of surfacedopant concentrations together with a high accuracy of evaluating the latter is achieved by incremental back-etching of t...

The thermal stability of hydrogenated amorphous silicon-passivated monocrystalline silicon wafers is investigated at different annealing times and temperatures. Stepwise thermal annealing was performed at temperatures ranging from 100 to 500 °C for 1, 5 and 15 min, respectively, and the effective minority carrier lifetime was measured after each an...

Anti-reflection coating (ARC) on crystalline silicon solar cell plays an important role in preventingpotential induced degradation (PID). In this work, we present a dual-layer ARC for increased resistance to potential induced degradation. By introducing a thin SiOyNx layer between the SiNx layer and the Si substrate, animproved chemical surface pas...

Several important semiconductor devices such as solar cells and photodetectors may be fabricated based on surface inversion layer junctions induced by fixed charge in a dielectric layer. Inversion layer junctions can easily be fabricated by depositing layers with a high density of fixed charge on a semiconducting substrate. Increasing the fixed cha...

In this work, films of a-Si:H films exhibiting low surface recombination velocities were deposited onto high lifetime silicon substrates and characterized. The films were made by plasma enhanced chemical vapour deposition with thicknesses ranging from 5 to 40 nm. On one set of samples, the a-Si:H layers was capped by a ∼100 nm layer of amorphous, h...

Neutron and X-ray reflectometry were used to determine the layer structure and hydrogen content of thin films of amorphous silicon (a-Si:H) deposited onto crystalline silicon (Si) wafers for surface passivation in solar cells. The combination of these two reflectometry techniques is well suited for non-destructive probing of the structure of a-Si:H...

A new technique to analyze the surface recombination for passivated silicon substrates has been employed to study the SiO2/c-Si interface under various band bending conditions. A photoluminescence imaging setup was used to measure the effective minority carrier lifetime of oxidized Si wafers while applying an external bias over the rear side passiv...

QSSPC-calibrated photoluminescence imaging (PLI) was used to determine the rear surface recombination velocity Srear,eff of p-type Si FZ wafers after processing of large area screen printed Al contacts with varying paste thickness and firing temperatures. The paste thickness was varied by changing the snap off in the screen printer, and the resulti...

PC1D is an open source computer program for simulation of crystalline semiconductor devices, and is the most commonly used simulation software in the solar cell community today. In this work we present a modified version of PC1D which runs from a command line, thus allowing for scripted simulations using any programming language. In order to increa...

In this paper, we study the surface passivation properties of thermally oxidized silicon wafers with controlled surface band bending, using a recently developed characterization technique combining calibrated photoluminescence imaging with the application of an external voltage over the rear side passivation layer. Various aspects of the technique...

Twenty different boron-doped Czochralski silicon materials have been analyzed for light-induced degradation. The carrier lifetime degradation was monitored by an automated quasi-steady-state photoconductance setup with an externally controlled bias lamp for in-situ illumination between measurements. Logarithmic plots of the time-resolved lifetime d...

In this work, we present a novel characterization technique for the analysis of Si surface passivation layers, using a photoluminescence imaging setup. In this technique the effective lifetime of passivated Si wafers is measured while applying an external bias over a rear side dielectric film. We demonstrate that this method can be used to analyze...

In this work we present an optimization of single- and double layer antireflection coatings (ARCs) for silicon solar cells. The wavelength-dependent reflectance and absorptance in the layers were calculated from experimental optical data measured on silicon nitride (a-SiNx:H) and oxynitride (a-SiOxNy:H) films deposited by plasma enhanced chemical v...

In order to reduce the costs of solar cells, there is a strong drive towards the use of thinner absorber materials. Crystalline silicon materials have already proven highly attractive as absorbers in mass produced, low cost and efficient solar cells. However as absorbers become thinner, crystalline silicon solar cells increasingly suffer from optic...

Title: Analysis of a-SiNx:H Passivated Si Surfaces Based on Injection Level Dependent Lifetime and Capacitance/Conductance-Voltage Measurements Abstract/Summary: In this paper, injection level dependent measurements of the effective surface recombination velocity (SRV) at silicon surfaces passivated with plasma-enhanced chemical vapor deposited...

Fourier-transform infrared spectroscopy (FTIR) and secondary-ion mass spectrometry (SIMS) have been employed to investigate the relation between the Li concentration and the strength of the 3577 cm−1 absorption line in five as-grown hydrothermal ZnO wafers. This line has previously been identified as a local vibrational mode of an OH molecule adjac...

The thermal stability of the prominent 3577 cm−1 infrared absorption band in ZnO, assigned to an O–H stretch mode adjacent to a Li atom on Zn site (LiZn), is studied. Employing slow sample cooling after annealing, the 3577 cm−1 peak remains at temperatures ≤ 1250 °C, consistent with previous reports. However, if the samples are cooled rapidly by qu...