Large area planar Ge p—n-photodiodes
Yu. M. Degot, O. N. Zabenkin, N. N. Kichina, N. V. Kravchanko, A. V. Kulymanov, Yu. V. Lobilov, O. V. Ogneva, M. A. Trishenkov, P. E. Khakuashev, I. V. Tchinareva
ORION Research-and-Production Association, Moscow, Russia
We describe the fabrication and performance of Ge p—n-photodiodes that have photosensitive areas with diameters of 1.1 mm. The photodiodes have hign sensitivity at 1.06 and 1.55 mm. The substrates used in this work are n-type wafers with a carrier concentration of 5Ч1015 cm-3. Boron ions are implanted to form a p—n-juction. To prevent edge breakdown the diode is surrounded by a guard ring prodused by berillium implantation. All implantations are performed with photoresist masks through the passivation layer, which acts as a screening oxide. Ti and Au are used as contacts. Typical responsivity is over 0.4 A/W at 1.06 mm, 0.7 A/W at 1.55 mm. At 20 °C, –10 V, the capacitance is 80 pF, dark current is 5 mkA.
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