Excimer laser doping techniques for II-VI semiconductors

Excimer laser doping technique has been utilized to obtain a heavy impurity doping in II-IV semiconductors which are considerably difficult materials to achieve bipolar conductivity and to obtain good ohmic contact on them during device fabrication. p-type heavy dopings were examined on CdTe, ZnSe and ZnO using dopant atoms such as Na, K, Sb, or P and diffusing them inside the crystals by irradiating with an excimer laser. Heavily doped layers with the resistivity in the range from 10(-2)-10(-3) Omega cm and the hole concentration of 10(17)-10(18) cm(-3) could be obtained. The carrier mobility in those doped p-type layers was in the range from 10-100 cm(2)/V-s. n-Type doping of CdTe was also investigated using In as a dopant. A highly conductive n-type layer with resistivity, electron concentration and mobility of 5 x 10(-3) Omega cm, 8.9 x 10(18) cm(-3) and 140 cm(2)/V-s, respectively, was successfully obtained. Finally, a CdTe p-i-n diode was fabricated which showed a very good potentiality to be used as a nuclear radiation detector. (C) 2001 Elsevier Science B.V. All rights reserved.