Predictable quantum efficient detector based onn-type silicon photodiodes

Abstract

Ikonen, E. (2017). Predictable quantum efficient detector based on n-type silicon photodiodes. Metrologia, 54(6) AbstractThe predictable quantum efficient detector (PQED) consists of two custom-made induced junction photodiodes that are mounted in a wedged trap configuration for the reduction of reflectance losses. Until now, all manufactured PQED photodiodes have been based on a structure where a SiO 2 layer is thermally grown on top of p-type silicon substrate. In this paper, we present the design, manufacturing, modelling and characterization of a new type of PQED, where the photodiodes have an Al 2 O 3 layer on top of n-type silicon substrate. Atomic layer deposition is used to deposit the layer to the desired thickness. Two sets of photodiodes with varying oxide thicknesses and substrate doping concentrations were fabricated. In order to predict recombination losses of charge carriers, a 3D model of the photodiode was built into Cogenda Genius semiconductor simulation software. It is important to note that a novel experimental method was developed to obtain values for the 3D model parameters. This makes the prediction of the PQED responsivity a completely autonomous process. Detectors were characterized for temperature dependence of dark current, spatial uniformity of responsivity, reflectance, linearity and absolute responsivity at the wavelengths of 488 nm and 532 nm. For both sets of photodiodes, the modelled and measured responsivities were generally in agreement within the measurement and modelling uncertainties of around 100 parts per million (ppm). There is, however, an indication that the modelled internal quantum deficiency may be underestimated by a similar amount. Moreover, the responsivities of the detectors were spatiallyOriginal content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. uniform within 30 ppm peak-to-peak variation. The results obtained in this research indicate that the n-type induced junction photodiode is a very promising alternative to the existing p-type detectors, and thus give additional credibility to the concept of modelled quantum detector serving as a primary standard. Furthermore, the manufacturing of PQEDs is no longer dependent on the availability of a certain type of very lightly doped p-type silicon wafers.

Characterization of a room temperature predictable quantum efficient detector for applications in radiometry and photometry

“…These trends of the dependence on the temperature and bias voltage are as expected. Former measurements of the dark photocurrent of a PQED of the same type 6 with 5 V bias applied [15] resulted in a higher dark photocurrent at room temperature (approx. 10 nA at 24 °C).…”

Predictable quantum efficient detector for low optical flux measurements

“…In addition to smaller doping concentration, set A photodiodes have 16 guard rings, whereas those of set B have only one. These factors lead to a decrease of dark current by a factor of five at room temperature for the set A photodiodes when compared against set B [9].…”

“…Over the last decade, the properties of the PQED have been studied comprehensively [1][2][3]5], and the PQED has been applied in various fields of optical metrology [6][7][8]. The characterization measurements have shown many appreciable properties, such as highcharge carrier collection efficiency [2,9], low reflectance [1], and linear response over seven orders of magnitude [2]. The uncertainty in the predicted responsivity of the PQED is below 100 parts per million (ppm) [1,9,10].…”

“…The characterization measurements have shown many appreciable properties, such as highcharge carrier collection efficiency [2,9], low reflectance [1], and linear response over seven orders of magnitude [2]. The uncertainty in the predicted responsivity of the PQED is below 100 parts per million (ppm) [1,9,10].…”

“…Originally, all PQED photodiodes were based on a structure of thermally grown silicon oxide ( SiO 2 ) on p-type silicon [1]. Recently, an alternative structure was demonstrated [9], where atomic layer deposition (ALD) was used to grow aluminium oxide ( Al 2 O 3 ) on top of n-type silicon. Two sets of n-type silicon induced-junction photodiodes were manufactured, denoted as set A and B, with respective doping concentrations of 2.5 × 10 11 cm −3 and 4.4 × 10 11 cm −3 .…”