HG0.4CD0.6TE 1.55-MU-M AVALANCHE PHOTODIODE NOISE-ANALYSIS IN THE VICINITY OF RESONANT IMPACT IONIZATION CONNECTED WITH THE SPIN-ORBIT SPLIT-OFF BAND

The authors describe the electrical and optical characterization of three Hg//1// minus //xCd//xGe avalanche photodiodes manufactured using planar technology with composition parameter x near 0. 6. This alloy composition leads to devices that are well suited for 1. 55- mu m detection. From the noise analysis under multiplication, the authors show the tight dependence of the ratio beta / alpha (of the hole and electron ionization coefficient, respectively) upon x and the ratio DELTA /E//g where DELTA is the spin-orbit splitting energy and E//g is the bandgap energy. It turns out that in these alloys around x equals 0. 6, DELTA is very close to bandgap energy so beta / alpha reaches its maximum value. Owing to this property, which is characteristic of II-VI compounds, Hg//1// minus //xCd//xTe is a good candidate for 1. 3- mu m to 1. 6- mu m avalanche photodiodes.