Role of f-elements in the growth of InP layers for radiation detectors

We report the effect of f-element addition (Er, Ho, Nd, Pr, Tb and Yb) during the liquid phase epitaxy (LPE) on the growth process and structural, electrical and optical propel-ties of thick InP epitaxial layers for applications in ionizing radiation detector structures. The layers were grown by LPE from the melt containing, besides essential components, also rare-earth (RE) elements admixture. The grown layers were examined by low-temperature photoluminescence spectroscopy and temperature-dependent Hall effect. We have demonstrated that the concentration of shallow donors was reduced effectively by up to three orders of magnitude. Room temperature Hall effect measurements revealed p-type conductivity of the layers prepared from the melt containing Tb, Pr or Yb admixture exceeding certain limiting concentration. From among the studied RE elements Pr and Tb appear as the most promising candidates for the preparation of pure and thick (d greater than or equal to 10 mum) InP layers with p-type conductivity. These layers could readily be used for the preparation of alpha -particles detectors, where detection will be mediated via the depletion layer of high quality Schottky contact.