Phosphorous Doping of Microcrystalline CVD Diamond Using Modified Conditions
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1039-P17-01
Phosphorous Doping of Microcrystalline CVD Diamond Using Modified Conditions Ken Haenen1,2, Andrada Lazea1,2, Vincent Mortet1,2, Jan D'Haen1,2, Peter Geithner3, and Jürgen Ristein3 1 Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Belgium 2 Division IMOMEC, IMEC vzw, Diepenbeek, Belgium 3 Technische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany ABSTRACT Phosphorous-doping of predominantly (110) oriented polycrystalline CVD diamond films is presented. Incorporation of phosphorous into the diamond grains was accomplished by using novel microwave plasma enhanced chemical vapor deposition (MW PE CVD) growth conditions. The substitutional nature of the phosphorous atom was confirmed by applying the quasi-steady-state photocurrent technique (PC) and cathodoluminescence (CL) measurements at low temperature. Topographical information and the relation between substrate and P-doped film grain orientation was obtained with scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). The optimized growth parameters for P-doped layers on (110) oriented polycrystalline diamond differ substantially from the standard conditions reported in literature for P-doping of single crystalline (111) and (100) oriented diamond surfaces. INTRODUCTION At present, the first report dealing with successful active n-type doping of CVD diamond is a decade old [1]. That breakthrough reinforced the position of diamond as the ideal future electronic material in “difficult” fields, such as high temperature, high frequency, and high power devices. Based on the availability of n-type doping and the realization of diamond pnjunctions, reports on devices making use of these achievements started to appear. Known demonstrators include light emitting diodes [2] and “solar blind” deep UV (VUV) detectors [3]. Since that time, many groups have proven that phosphorous doping can be reproducibly achieved by various deposition techniques and several precursor sources [4,5]. Phosphorous-doped layers of superior quality with high electron mobility [6] became available, and even the difficult problem to grow on (001) oriented substrates was tackled [7]. Recently, the use of such layers yielded a highly efficient UV-emitting p-i-n-junction [8] based on the superior quality of (001) oriented B-doped layers as opposed to the (111) counterpart. Even so, the amount of applications making use of n-type diamond remains limited up to now. Partly, the reason can be found in the rather deep nature of the P-donor, making it insufficiently ionized at room temperature, but it is clear that there are also more technical limitations that need to be overcome. Examples are the limited size of the samples, complicating processing, and the extremely low doping efficiency on (100) oriented diamond substrates [9]. In an attempt to overcome these problems a polycrystalline P-doped n-type diamond layer could prove to be beneficial. First results have proven that n-type conductivity and relatively high P
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