Molecular beam epitaxy of in1-xGaxASyP1-y(y ≃2.2 ×) lattice matched to InP using gas cells

Abstract

In this paper we report MBE growth of quaternary alloys In1-xGaxAsyP1-y (y≃2.2x, 0 <y < 1) lattice matched to InP, by using gas cells as sources of V elements. The growth is performed in a MBE system which can receive both gas and solid cells. An efficient pumping system made from association of cryo and turbo molecular pumps allows a background hydrogen pressure of ≃ 10-5 Torr during the growth. Gas sources produce P2 and As2 flux from cracking of PH3 and AsH3. An accurate and flexible control of P2 and As2 flux is obtained by monitoring the gas cells by a mass selector system. Electron probe analysis and X-ray diffraction show that reproducible growth of homogeneous quaternary layers with a precise control of the composition can be achieved with gas cells. Possible contamination by residual impurities coming from the cracking furnace is investigated by low temperature photoluminescence (8 K). Typical spectrum (8 K) exhibits a narrow near band edge peak (FWHM = 17 meV) and a secondary peak located at 14 meV below the first one which is attributed to carbon acceptor impurity. Room temperature photoluminescence efficiency is equal to that obtained by LPE. For In0.60Ga0.40As0.90Po0.10 background carrier concentration isn = 1016cm-3 with electron mobilities μ (300 K) = 6000 cm2/Vsec and μ (77 K) = 13000 cm2/Vsec.