Electrostatics of the Nanowires with Radial …
91
Figure 9 represents the voltage dependences of the nanowire p-i-n diode capacitance given by formula (27) for three doping combinations as a function of the
distance between the i-layer and center of the nanowire at the same value of the
i-layer thickness equal to 20 nm.
As it follows from these figures, capacitance of the nanowire p-i-n diode decreases
when the i-layer is moving away from the nanowire center at N A = N D and N A >>
N D and, on the contrary, increases at N A << N D . In any case, the voltage dependence
of the capacitance diminishes as it has to be in planar p-i-n diode [21].
5 Conclusion
Thus, distinction of nanowire radial p-n junction electrostatics from electrostatics of
analogous planar structures is conditioned by overlaying specific falling of the builtin electric field with radial coordinate (due to cylindrical geometry of the structure)
on usual planar situation. As a result, electric field of the radial p-n junction proves
to be nonsymmetrical even at symmetrical doping levels of both sides. And electric
field in i-layer of a p-i-n diode acquires falling character.
Increase in the core depletion width with decrease in the p-n junction radius and
simultaneous decrease in the shell depletion width can be important in such devices
as heterostructure solar cells because this results in change of the relative contribution
to the performance characteristics from the different constituent materials. Namely,
the lesser the radius of the heterostructure p-n junction, the larger is contribution
from the core material (under equal other conditions).
It should be noted that at the small p-n junction radiuses, dependence of 1/C
2
on applied voltage, being nonlinear, cannot be used for determination of the built-in
potential and doping level of the junction as it made usually in the case of planar
structures.
Acknowledgements This work was supported by the National Academy of Sciences of Ukraine
[project 2.2.6.34].
References
1. Luscombe JH, Frenzen CL (2002) Solid-State Electron 46(6):885–889
2. Nersesyan SR, Petrosyan SG (2012) Semicond Sci Technol 27(12):125009
3. Borblik VL (2015) Solid-State Electron 114:171–173
4. Tian B, Zheng X, Kempa TJ, Fang Y, Yu N, Yu G, Huang J, Lieber CM (2007) Nature 449:885–
890
5. Soci C, Zhang A, Bao X-Y, Kim H, Lo Y, Wang D (2010) J Nanosci Nanotechnol 10(3):1430–
1449
6. Hua B, Motohisa J, Kobayashi Y, Hara S, Fukui T (2009) Nano Lett 9(1):112–116
7. Chia ACE, LaPierre RR (2013) J Appl Phys 114(7):074317
8. Petrosyan S, Yesayan A, Nersesyan S (2012) World Acad Sci Eng Technol 71:1065–1070
91
Figure 9 represents the voltage dependences of the nanowire p-i-n diode capacitance given by formula (27) for three doping combinations as a function of the
distance between the i-layer and center of the nanowire at the same value of the
i-layer thickness equal to 20 nm.
As it follows from these figures, capacitance of the nanowire p-i-n diode decreases
when the i-layer is moving away from the nanowire center at N A = N D and N A >>
N D and, on the contrary, increases at N A << N D . In any case, the voltage dependence
of the capacitance diminishes as it has to be in planar p-i-n diode [21].
5 Conclusion
Thus, distinction of nanowire radial p-n junction electrostatics from electrostatics of
analogous planar structures is conditioned by overlaying specific falling of the builtin electric field with radial coordinate (due to cylindrical geometry of the structure)
on usual planar situation. As a result, electric field of the radial p-n junction proves
to be nonsymmetrical even at symmetrical doping levels of both sides. And electric
field in i-layer of a p-i-n diode acquires falling character.
Increase in the core depletion width with decrease in the p-n junction radius and
simultaneous decrease in the shell depletion width can be important in such devices
as heterostructure solar cells because this results in change of the relative contribution
to the performance characteristics from the different constituent materials. Namely,
the lesser the radius of the heterostructure p-n junction, the larger is contribution
from the core material (under equal other conditions).
It should be noted that at the small p-n junction radiuses, dependence of 1/C
2
on applied voltage, being nonlinear, cannot be used for determination of the built-in
potential and doping level of the junction as it made usually in the case of planar
structures.
Acknowledgements This work was supported by the National Academy of Sciences of Ukraine
[project 2.2.6.34].
References
1. Luscombe JH, Frenzen CL (2002) Solid-State Electron 46(6):885–889
2. Nersesyan SR, Petrosyan SG (2012) Semicond Sci Technol 27(12):125009
3. Borblik VL (2015) Solid-State Electron 114:171–173
4. Tian B, Zheng X, Kempa TJ, Fang Y, Yu N, Yu G, Huang J, Lieber CM (2007) Nature 449:885–
890
5. Soci C, Zhang A, Bao X-Y, Kim H, Lo Y, Wang D (2010) J Nanosci Nanotechnol 10(3):1430–
1449
6. Hua B, Motohisa J, Kobayashi Y, Hara S, Fukui T (2009) Nano Lett 9(1):112–116
7. Chia ACE, LaPierre RR (2013) J Appl Phys 114(7):074317
8. Petrosyan S, Yesayan A, Nersesyan S (2012) World Acad Sci Eng Technol 71:1065–1070