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A delta-doped quantum well system with additional modulation doping.

Luo DS, Lin LH, Su YC, Wang YT, Peng ZF, Lo ST, Chen KY, Chang YH, Wu JY, Lin Y, Lin SD, Chen JC, Huang CF, Liang CT - Nanoscale Res Lett (2011)

Bottom Line: In situ titled-magnetic field measurements reveal that the observed direct I-QH transition depends on the magnetic component perpendicular to the quantum well, and the electron system within this structure is 2D in nature.Furthermore, transport measurements on the 2DEG of this study show that carrier density, resistance and mobility are approximately temperature (T)-independent over a wide range of T.Such results could be an advantage for applications in T-insensitive devices.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, National Tsinghwa University, Hsinchu, 300, Taiwan. lihung@mail.ncyu.edu.tw.

ABSTRACT
A delta-doped quantum well with additional modulation doping may have potential applications. Utilizing such a hybrid system, it is possible to experimentally realize an extremely high two-dimensional electron gas (2DEG) density without suffering inter-electronic-subband scattering. In this article, the authors report on transport measurements on a delta-doped quantum well system with extra modulation doping. We have observed a 0-10 direct insulator-quantum Hall (I-QH) transition where the numbers 0 and 10 correspond to the insulator and Landau level filling factor ν = 10 QH state, respectively. In situ titled-magnetic field measurements reveal that the observed direct I-QH transition depends on the magnetic component perpendicular to the quantum well, and the electron system within this structure is 2D in nature. Furthermore, transport measurements on the 2DEG of this study show that carrier density, resistance and mobility are approximately temperature (T)-independent over a wide range of T. Such results could be an advantage for applications in T-insensitive devices.

No MeSH data available.


Related in: MedlinePlus

Electrical measurements over a wide range of temperature:(a) Resistivity as a function of temperature ρxx(T), (b) carrier density as a function of temperature n(T), and (c) mobility as a function of temperature μ(T).
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Figure 2: Electrical measurements over a wide range of temperature:(a) Resistivity as a function of temperature ρxx(T), (b) carrier density as a function of temperature n(T), and (c) mobility as a function of temperature μ(T).

Mentions: As mentioned earlier, it is highly desirable to obtain a thorough understanding of the basic properties of our system so as to fully realize its potential in electronic and optoelectronic devices. Figure 2a shows resistivity measurements as a function of T over a wide range of temperature. Interestingly, ρxx is almost T-independent from room temperature down to 23 K. To understand why ρxx at B = 0 is insensitive to the temperature, the T-dependence of n is investigated, and μ is obtained using ρxx = 1/neμ at zero magnetic field, as shown in Figure 2b, c. The carrier concentration does not decrease too much, and thus the 2DEG does not suffer from the carrier freeze-out at low temperatures because of the extra modulation doping. While μ increases with decreasing T in most 2DEG because of the reduced electron-phonon scattering, it can bee seen from Figure 2c that μ saturates and remains at approximately 0.37 m2/v/s from T = 230 K. For a 2DEG in the delta-doped quantum well, with decreasing T, it shall be considered that the enhancement of the multiple scattering may decrease the mobility and thus compensate the reduced electron-phonon scattering effect [6,7]. Therefore, we can design the devices insensitive to T by using the delta-doped quantum well with the extra modulation doping. For example, when designing a circuit for a low-temperature amplifier, such as the one used for space technology and satellite communications, one needs to perform a test at room temperature (RT) first. When cooling down the amplifier, its characteristics can be significantly different since the resistance of the device based on HEMT structure may be a lot lower than that at RT [24]. Therefore substantial variation in the circuitry design based on the RT test is required. Since the ρxx, n and μ of our structure are almost T-independent over a wide range of temperature, a RT test may be sufficient.


A delta-doped quantum well system with additional modulation doping.

Luo DS, Lin LH, Su YC, Wang YT, Peng ZF, Lo ST, Chen KY, Chang YH, Wu JY, Lin Y, Lin SD, Chen JC, Huang CF, Liang CT - Nanoscale Res Lett (2011)

Electrical measurements over a wide range of temperature:(a) Resistivity as a function of temperature ρxx(T), (b) carrier density as a function of temperature n(T), and (c) mobility as a function of temperature μ(T).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211186&req=5

Figure 2: Electrical measurements over a wide range of temperature:(a) Resistivity as a function of temperature ρxx(T), (b) carrier density as a function of temperature n(T), and (c) mobility as a function of temperature μ(T).
Mentions: As mentioned earlier, it is highly desirable to obtain a thorough understanding of the basic properties of our system so as to fully realize its potential in electronic and optoelectronic devices. Figure 2a shows resistivity measurements as a function of T over a wide range of temperature. Interestingly, ρxx is almost T-independent from room temperature down to 23 K. To understand why ρxx at B = 0 is insensitive to the temperature, the T-dependence of n is investigated, and μ is obtained using ρxx = 1/neμ at zero magnetic field, as shown in Figure 2b, c. The carrier concentration does not decrease too much, and thus the 2DEG does not suffer from the carrier freeze-out at low temperatures because of the extra modulation doping. While μ increases with decreasing T in most 2DEG because of the reduced electron-phonon scattering, it can bee seen from Figure 2c that μ saturates and remains at approximately 0.37 m2/v/s from T = 230 K. For a 2DEG in the delta-doped quantum well, with decreasing T, it shall be considered that the enhancement of the multiple scattering may decrease the mobility and thus compensate the reduced electron-phonon scattering effect [6,7]. Therefore, we can design the devices insensitive to T by using the delta-doped quantum well with the extra modulation doping. For example, when designing a circuit for a low-temperature amplifier, such as the one used for space technology and satellite communications, one needs to perform a test at room temperature (RT) first. When cooling down the amplifier, its characteristics can be significantly different since the resistance of the device based on HEMT structure may be a lot lower than that at RT [24]. Therefore substantial variation in the circuitry design based on the RT test is required. Since the ρxx, n and μ of our structure are almost T-independent over a wide range of temperature, a RT test may be sufficient.

Bottom Line: In situ titled-magnetic field measurements reveal that the observed direct I-QH transition depends on the magnetic component perpendicular to the quantum well, and the electron system within this structure is 2D in nature.Furthermore, transport measurements on the 2DEG of this study show that carrier density, resistance and mobility are approximately temperature (T)-independent over a wide range of T.Such results could be an advantage for applications in T-insensitive devices.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, National Tsinghwa University, Hsinchu, 300, Taiwan. lihung@mail.ncyu.edu.tw.

ABSTRACT
A delta-doped quantum well with additional modulation doping may have potential applications. Utilizing such a hybrid system, it is possible to experimentally realize an extremely high two-dimensional electron gas (2DEG) density without suffering inter-electronic-subband scattering. In this article, the authors report on transport measurements on a delta-doped quantum well system with extra modulation doping. We have observed a 0-10 direct insulator-quantum Hall (I-QH) transition where the numbers 0 and 10 correspond to the insulator and Landau level filling factor ν = 10 QH state, respectively. In situ titled-magnetic field measurements reveal that the observed direct I-QH transition depends on the magnetic component perpendicular to the quantum well, and the electron system within this structure is 2D in nature. Furthermore, transport measurements on the 2DEG of this study show that carrier density, resistance and mobility are approximately temperature (T)-independent over a wide range of T. Such results could be an advantage for applications in T-insensitive devices.

No MeSH data available.


Related in: MedlinePlus