N-type doping of Ge by P spin on dopant and pulsed laser melting

N-type doping of Ge based on spin on dopant sources and pulsed laser melting has been proposed as an alternative to the use of complex and expensive techniques such as ion-implantation or molecular beam epitaxy. Optimization of the n+/p junction has been carried out with a KrF laser (of 22 ns pulse duration) by studying the effect of different laser fluences and the number of pulses. The diffusion profiles, sheet resistance, carrier density and mobility have been determined by secondary ion mass spectrometry and Van der Pauw-Hall measurements. By properly selecting the range of laser energy density and number of pulses, a high level of activation (>1019 cm-3) with good mobility (350-450 cm2 V-1 s-1) and low sheet resistance (<50 Ω/□) has been achieved. In addition, the good crystalline quality of the samples has been confirmed by high-resolution x-ray diffraction measurements, demonstrating the viability of such a low-cost manufacturing process for next generation Ge-based devices.