Crystal orientation dependence of ionization rates in germanium

Abstract

Ionization rates in 〈111〉 and 〈100〉 germanium are determined experimentally. The ionization rates obtained are expressed as α=2.72×106 exp(−1.1×106/E), β=1.72×106 exp(−9.37×105/E) for 〈111〉 and α=8.04×106 exp(−1.4×106/E), β=6.39×106 exp(−1.27×106 /E) cm−1 for 〈100〉 where α and β are ionization rates for electrons and holes, respectively, and E is the electric field. Hole- to electron-ionization-rate ratios of 〈100〉 Ge are found to be greater than those of 〈111〉 Ge. The multiplication noise power of Ge avalanche photodiodes calculated by using the ionization rates obtained shows good agreement with experimental results.

Germanium avalanche receiver for low power interconnects

“…The multiplication process is initiated by electrons and holes, and both are multiplied within the intrinsic region. According to the impact ionization theory [21][22][23][24] , a high excess noise factor should then be obtained as electrons and holes have quite similar impact ionization coefficients in Ge 25 . However, a narrow width multiplication region (500 nm) was chosen in the design to promote a large dead space effect 23,26 contribution favouring an efficient reduction of the excess noise factor.…”

Impact Ionization MOS (I-MOS)—Part I: Device and Circuit Simulations

“…Germanium (Ge) was chosen as the material of choice in the I-MOS because its for both electrons and holes are much higher than in Si [14], [15]. In Si, is much lower than [16].…”

“…Impact-ionization coefficients were calibrated to available experimental data on Ge devices [14], [15]. Fig.…”

Possible Realization of Near Optimum Efficiency from n-Si-Ge/p-Ge-Si DDR Hetero Structure IMPATT Diode

“…The materials parameters of both the materials are taken from recent experimental reports [8][9][10] are shown in Table 1 The ionization rate in Ge is observed to be higher by an order of magnitude than Si at the same electric field. The gap in the values of carrier ionization rate in Si and Ge further widens as the Ge layer remains near the high field junction plane where as Si layer is considered away from the junction.…”

“…Material parameters like the ionization rate, drift velocities etc., of all the materials have been taken from the recently reported published literature [8][9][10]. The diode active layer width is divided into large number of space steps of 1 nm per micron or less.…”