DOI: 10.18150/a8mokr
title: P-type conductivity in GaN:Be epitaxial layers - source data

description: Electron transport properties of Be-doped heteroepitaxial GaN layers grown by Metalorganic Vapor Phase Epitaxy were investigated by means of temperature-dependent Hall effect measurements. The Be concentration was in the range of 4×1018-3×1019 cm-3. P-type conductivity (not over-compensated by Be-related donors) from the isolated substitutional BeGa acceptors was revealed in all studied samples, with the highest room-temperature hole concentration of 4×1013 cm-3 for the most conductive sample. Resistivity of 10 kΩ cm and mobility of about 15 cm2/Vs were achieved. The conductivity decreased with increasing Be concentration, strongly indicating a self-compensation mechanism. Quantitative analysis of temperature-dependent Hall effect data showed a relatively deep position of the BeGa acceptor level, at EV+0.40 eV. This finding is consistent with the deep polaronic state of the Be acceptor revealed in previous optical and theoretical studies.The source data to the publication "P-type conductivity in GaN:Be" epitaxial layers (J. Appl.Phys.) contain the following materials.Source material to Fig. 1. I-V characteristics of two van der Pauw configurations of current and voltage probes (used for resistivity evaluation - V34 vs I12 and V41 vs I23) at RT, showing ohmic properties of the sample.Source Material to Fig. 2a and 2b. The dependence of the Hall voltage on magnetic field for sample #1 at room temperature (a) and at T = 476.6 K (b). Calculation of resistivity ro from the deposited source data was made according to the formula:ro=pi/ln(2)*d*I)*0.25*(Vdp1p-Vdp1m+Vdp2p-Vdp2m)I-current intensity.Vdp1p,Vdp2p - voltages measured at two van der Pauw configurations under positive current polarization.Vdp1m,Vdp2m - voltages measured at two van der Pauw configurations under negative current polarization.d=0.5 mikro-meter - thickness of the layer.Under the specific configuration of current, voltages (Vh1, Vh2) and magnetic field intensity (B) used in our experimental set-up the Hall voltages were calculated according to the formula:Vh=[(Vh1p-Vh1m)/2-(Vh2p-Vh2m)/2], whereVh1p,Vh2p - voltages measured at two different diagonal contact configuration under positive current polarization.Vdp1m,Vdp2m - voltages measured at two different diagonal contact configuration under negative current polarization.Conductivity type, carrier concentration (n or p) was evaluated from the sign and the value of the slope of the Vh(B), derived from its linear fit. Thus, the derivative d(Vh)/dB=IB/(qnd), where q=+e - elementary charge of hole (p-type conductivity, n=p) or q=-e - elementary charge of electron (n-type conductivity).Mobility of holes: mi=1/(ro*e*p), where ro,p were obtained previously.Source data to Fig 3a (hole concentration), 3b (resistivity) and 3c (mobiity) for samples with low, medium and high Be concentration.For each temperature point and each sample p,ro and mi were calculated from the deposited source data using the same procedure as in previous point.Data to Fig. 4, i.e. p/T^1.5 vs 1000/T dependance in order to obtain location of Be acceptor level for GaN:Be of low, medium and high concentration of Be.