Investigation of implanted gallium depth distributions in ZnSxSe-x by EPMA

Abstract

Abstract. In the present work EPMA combined with Monte Carlo simulation was applied to investigate implanted gallium depth distributions in ZnSxSel_x layers. The layers of about 1 to 4 #m thickness were grown by MOVPE on (100)-GaAs substrate. The overlap of the Ga and zinc L X-ray spectra and the low gallium net count rates were overcome by stripping the spectra of non implanted layers and by applying appropriate beam currents and counting times. Capabilities and limitations of the EPMA technique as applied to depth profile analysis are demonstrated.Despite the mentioned L interference, the detectability limit of EPMA for 340 keV Ga in ZnSxSe 1 -x is as low as 1014 cm -2. The measured Ga Le intensity versus beam energy curves reveal variations of the Ga depth profiles during annealing. Evaluation of the intensity curves by means of Monte Carlo simulations yields the implanted dose densities and the first two moments of the depth distributions, i.e. the projected range and its standard deviation. The nonannealed profiles agree well with expectations, but after thermal annealing the profiles were significantly shifted towards the surface. Comparison of EPMA and SIMS results with the example of a non annealed profile in ZnSe has shown good agreement.Key words: ion implanation, depth profile analysis, II/VI semiconductors, MOVPE, EPMA.Electron probe X-ray microanalysis (EPMA) is a well established technique for quantitatively analysing solids on a microscopic scale [1]. During the last decade it has been further developed for analysing thin films and multilayers on substrates [2,3,4]. Recently, also the possibility of analysing implanted elements by EPMA was demonstrated [5, 6].

EPMA Sputter Depth Profiling: A New Technique for Quantitative in-Depth Analysis of Layered Structures

“…All EPMAtechniques presuppose that the single layers exhibit no compositional inhomogeneities over their depth. But even if this were the case, EPMA could resolve such depth profiles under certain limited circumstances and with investment of great effort by applying many different electron energies to scan the center of excitation over the depth of the sample [8][9][10][11].…”