scholarly journals Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

Open Physics ◽  
2012 ◽  
Vol 10 (2) ◽  
Author(s):  
Ozlem Celik ◽  
Engin Tiras ◽  
Sukru Ardali ◽  
Sefer Lisesivdin ◽  
Ekmel Ozbay
Keyword(s):  
Raman Spectroscopy ◽  
Hall Effect ◽  
Optical Phonon ◽  
Electron Mobility ◽  
Phonon Scattering ◽  
Impurity Scattering ◽  
Interface Roughness ◽  
Polar Optical Phonon ◽  
Optical Phonon Scattering ◽  
Hall Effect Measurements

AbstractThe longitudinal optical (LO) phonon energy in AlGaN/GaN heterostructures is determined from temperature-dependent Hall effect measurements and also from Infrared (IR) spectroscopy and Raman spectroscopy. The Hall effect measurements on AlGaN/GaN heterostructures grown by MOCVD have been carried out as a function of temperature in the range 1.8-275 K at a fixed magnetic field. The IR and Raman spectroscopy measurements have been carried out at room temperature. The experimental data for the temperature dependence of the Hall mobility were compared with the calculated electron mobility. In the calculations of electron mobility, polar optical phonon scattering, ionized impurity scattering, background impurity scattering, interface roughness, piezoelectric scattering, acoustic phonon scattering and dislocation scattering were taken into account at all temperatures. The result is that at low temperatures interface roughness scattering is the dominant scattering mechanism and at high temperatures polar optical phonon scattering is dominant.

scholarly journals Temperature and electric field dependences of the mobility of electrons in vertical transport in GaAs/Ga1−y AlyAs barrier structures containing quantum wells

Open Physics ◽  
2008 ◽  
Vol 6 (3) ◽  
Author(s):  
Safi Altunöz ◽  
Hüseyin Çelik ◽  
Mehmet Cankurtaran
Keyword(s):  
Quantum Wells ◽  
Applied Voltage ◽  
Phonon Scattering ◽  
Impurity Scattering ◽  
Vertical Transport ◽  
Interface Roughness ◽  
Polar Optical Phonon ◽  
Optical Phonon Scattering ◽  
Interface Roughness Scattering ◽  
The Difference

AbstractThe mobility of electrons in vertical transport in GaAs/Ga1−y AlyAs barrier structures was investigated using geometric magnetoresistance measurements in the dark. The samples studied had Ga1−y AlyAs (0 ≤ y ≤ 0:26) linearly graded barriers between the n+-GaAs contacts and the Ga0:74Al0:26As central barrier, which contain N w (=0, 2, 4, 7 and 10) n-doped GaAs quantum wells. The mobility was determined as functions of (i) temperature (80–290 K) at low applied voltage (0.01–0.1 V) and (ii) applied voltage (0.005–1.6 V) at selected temperatures in the range 3.5–290 K. The experimental results for the temperature dependence of low-field mobility suggest that space-charge scattering is dominant in the samples with N w=0 and 2, whereas ionized impurity scattering is dominant in the samples with N w=4, 7 and 10. The effect of polar optical phonon scattering on the mobility becomes significant in all barrier structures at temperatures above about 200 K. The difference between the measured mobility and the calculated total mobility in the samples with N w=4, 7 and 10, observed above 200 K, is attributed to the reflection of electrons from well-barrier interfaces in the quantum wells and interface roughness scattering. The rapid decrease of mobility with applied voltage at high voltages is explained by intervalley scattering of hot electrons.

Analytical Theory of Electron Mobility and Drift Velocity in GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
B. L. Gelmont ◽  
M. S. Shur ◽  
M. Stroscio
Keyword(s):  
Electric Fields ◽  
Drift Velocity ◽  
Optical Phonon ◽  
Electron Mobility ◽  
Phonon Scattering ◽  
Electron Gas ◽  
Transport Equations ◽  
Polar Optical Phonon ◽  
Two Dimensional ◽  
Optical Phonon Scattering

ABSTRACTWe derive balance transport equations for the electron mobility and drift velocity, which are applicable at any degeneracy of the electron gas. These equations account for the polar optical phonon scattering and ionized impurity scattering and include the effects of screening. These equations are valid only for very high concentrations (above 1019 cm-3 for GaN). However, the comparison with the results of Monte Carlo simulations shows that they fairly accurately reproduce the field-velocity curves in GaN in moderate electric fields (up to 100 kV/cm). The comparison with the electron mobility calculated using the two-step model [1] shows a much larger difference but allows us to illustrate the trends in mobility dependencies caused by electron-electron collisions. We also derive the balance transport equations accounting for the polar optical phonon scattering in a two-dimensional electron gas. The calculations based on these equations, show that the unscreened polar optical scattering mobility is smaller in the two-dimensional gas than in the bulk intrinsic semiconductor and that the mobility decreases with the decrease of the quantum well thickness.

Polar Optical Phonon Instability and Intervalley Transfer in Gallium Nitride

1998 ◽  
Vol 512 ◽  
Author(s):  
B. E. Foutz ◽  
S. K. O'leary ◽  
M. S. Shur ◽  
L. F. Eastman ◽  
B. L. Gelmont ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Analytical Model ◽  
Optical Phonon ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Polar Optical Phonon ◽  
Scattering Mechanism ◽  
Loss Mechanism ◽  
One Dimensional ◽  
Optical Phonon Scattering

ABSTRACTWe develop a simple, one-dimensional, analytical model, which describes electron transport in gallium nitride. We focus on the polar optical phonon scattering mechanism, as this is the dominant energy loss mechanism at room temperature. Equating the power gained from the field with that lost through scattering, we demonstrate that beyond a critical electric field, 114 kV/cm at T = 300 K, the power gained from the field exceeds that lost due to polar optical phonon scattering. This polar optical phonon instability leads to a dramatic increase in the electron energy, this being responsible for the onset of intervalley transitions. The predictions of our analytical model are compared with those of Monte Carlo simulations, and are found to be in satisfactory agreement.

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