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The Au/Ti/n-GaAs structures with and without Al_2O_3 interfacial layer have been fabricated.The Al_2O_3interfacial layer has been formed on the GaAs substrate by atomic layer deposition.The effects of the interfacial layer on the current-voltage(I-V) and capacitance-voltage(C-V) characteristics of the devices have been investigated in the temperature range of 60-300 K.It has been seen that the carrier concentration from C-V characteristics for the MIS(metal/insulating layer/semiconductor) diode with Al_2O_3 interfacial layer has a higher value than that for the reference diode without the Al_2O_3 interfacial layer(MS).Such a difference in the doping concentration has been attributed not to doping variation in the semiconductor bulk but to the presence of the Al_2O_3 interfacial layer because both diodes have been made on the pieces cut from the same n-type GaAs wafer.The temperaturedependent I-V characteristics of the MIS diode do not obey the thermionic emission current theory because of the presence of the Al_2O_3 layer.An electron tunneling factor,aδ(x)~(1/2),value of 20.64 has been found from the I-V-T data of the MIS diode.An average value of 0.627 eV for the mean tunneling barrier height,x,presented by the Al_2O_3 layer has been obtained.
The Au / Ti / n-GaAs structures with and without Al_2O_3 interfacial layer have been fabricated. The Al_2O_3 interfacial layer has been formed on the GaAs substrate by atomic layer deposition. The effects of the interfacial layer on the current-voltage (IV) and capacitance It has been seen that the carrier concentration from CV characteristics for the MIS (metal / insulating layer / semiconductor) diode with Al 2 O 3 interfacial layer has a higher value than that for the reference diode without the Al 2 O 3 interfacial layer (MS) .Such a difference in the doping concentration has been attributed not to doping variation in the semiconductor bulk but to the presence of the Al 2 O 3 interfacial layer because both diodes have been made on the pieces cut from the same n-type GaAs wafer. temperature dependent IV characteristics of the MIS diode do not obey the thermionic emission current theory because of the presence of the Al 2 O 3 layer. An electron tunneling factor, a δ (x) ~ (1/2), the value of 20.64 has been found from the IVT data of the MIS diode. An average value of 0.627 eV for the mean tunneling barrier height, x, presented by the Al 2 O 3 layer has been obtained.