M. A. Zaidi

Defects in electron irradiated GaInP

We present a characterization of the defects created by electron irradiation at room temperature in n‐type GaInP. Four electron traps, labeled E1–E4, and no hole traps have been detected using deep level transient spectroscopy in the temperature range 4–400 K. The corresponding energy levels and barriers associated with electron capture have been measured. The introduction rates, ranging from 4×10−3 to 0.4 cm−1, indicate that these defects are probably not primary defects but complexes resulting from the interaction of these primary defects between themselves or with impurities. This is not surprising, owing to the fact that defect annealing takes place below 300 K in InP.

Defects in epitaxial Si‐doped GaInP

We have characterized by capacitance‐voltage and deep level transient spectroscopy measurements the only defect detected in Si‐doped GaInP layers. This defect exhibits an ionization energy of 0.435 eV but is located only at ∼20 meV below the bottom of the conduction band. All its characteristics, i.e., energy level, apparent capture barrier, ionization energy, can be understood if the defect is a donor associated DX center. Its cross section for electron and hole capture have been measured. The effect of an electric field on the ionization energy confirms that the defect is indeed shallow and a donor.

Deep‐level analysis of n‐type GaAs1−xPx alloys

Deep‐level transient spectroscopy has been used to study the properties of electron and hole traps present in n‐type GaAs1−xPx alloys and their evolution versus the alloy composition. An electron trap labeled E0 is observed for all values of the alloy composition x, while a second electron trap E1 appears only for 1≳x≥0.81. As for hole traps one (H2) appears for 1≳x≥0.75, while two others, H0 and H1, are detected for x≥0.81 and for 1≳x≥0.81, respectively. Their ionization energies have been determined and the barriers, associated with electron capture, have been measured in order to determine the energetic position of the two electron traps relative to the conduction band.

Defects in electron‐irradiated GaAlAs alloys

Using deep‐level transient spectroscopy, we have characterized the energy levels, barriers for electron capture, and introduction rates of the defects introduced by electron irradiation in liquid‐phase epitaxy grown n‐type (Te)Ga1−xAlxAs layers of various alloy composition (x=0.25, 0.40, 0.60, and 0.80). We observed five defects which present various type behaviors: energy levels linked to the valence band or to the L conduction bands, constant barriers, or varying in a manner consistent with the band structure. These results are in agreement with the understanding obtained previously on electron‐induced defects in GaAs.

Defects in electron irradiated n‐type GaP

The characteristic ionization energies, barriers associated with capture, energy levels, and introduction rates of the various electron and hole traps introduced by electron irradiation in n‐type GaP are determined using deep level transient spectroscopy. The same traps are created after 4 or 300 K irradiation. Their introduction rates correspond to those expected for primary displacements. From the similarity to the case of GaAs, we conclude that the corresponding defects are intrinsic defects (isolated vacancies and vacancy interstitial pairs) associated with the P (electron traps) and Ga (hole traps) sublattices.

Recombination centers in Czochralski‐grown p‐Si

A sensitive deep‐level transient spectrometer operating in the range 300–600 K has been used to detect the defect responsible for the minority‐carrier lifetime in p‐type Czochralski‐grown Si. The characteristics of this defect (energy level, barrier for hole capture, hole and electron capture rates, and concentration) have been determined. This level is, as expected, located near the middle of the forbidden gap. We verified that it is indeed responsible for the lifetime by a comparison between the calculated value and the result of direct measurements. If this defect is an impurity, it could be manganese.

Effect of surface passivation by SiN/SiO2 of AlGaN/GaN high-electron mobility transistors on Si substrate by deep level transient spectroscopy method

Device performance and defects in AlGaN/GaN high-electron mobility transistors have been correlated. The effect of SiN/SiO2 passivation of the surface of AlGaN/GaN high-electron mobility transistors on Si substrates is reported on DC characteristics. Deep level transient spectroscopy (DLTS) measurements were performed on the device after the passivation by a (50/100 nm) SiN/SiO2 film. The DLTS spectra from these measurements showed the existence of the same electron trap on the surface of the device.

The DX center in GaAsP alloys

Using Deep Level Transient Spectroscopy (DLTS), we have investigated the properties of the DX center in GaAsP for the whole range of alloy composition x. We have determined the variation of the defect characteristics (thermal ionization energy E i , barrier for electron capture B, and energy level location E DX ) versus x. From the relationship that exists between E i , B and E DX , and between B and Δ, the energy difference between the L band and the bottom of the conduction band, we deduce that electron emission and capture occur from and to the DX center via the L band in the same fashion as in GaAlAs alloys. A good fit of the variation of E i and B versus x is obtained in a model where the DX level is a donor state associated with the L band which is 200 meV deep, like in GaAlAs, as a result of intervalley mixing.

Electron/transport in (Mo/Au)/AlGaN/GaN Schottky diode

The knowledge of the conduction mechanisms in a Schottky barrier is essential to calculate the Schottky barrier parameters and to explain the observed effects. In the present work, we report temperature- dependent current-voltage characteristics of (Mo/Au)/Al0.26Ga0.74N/GaN/Si/ Schottky barrier diodes. Measurements were performed in the temperature range of 80 -300 K.Results have been explained based on the thermionic emission mechanism with lateral inhomogeneity at the (Mo/Au/AlGaN/GaN/Si) interface. As is shown, the barrier height ΦB0 as well as the ideality factor n exhibit an important temperature dependence and the anomaly resulting from this dependence has been explained by invoking two sets of Gaussian distributions at the metal/semiconductor interface for temperature ranging from 80 K to 160 K and from 160K to300 K, respectively. It is also found that the values of Rs obtained from Cheungs method strongly depend on temperature and decrease with decreasing temperature. Keywords: Schottky barrier, Current-voltage characteristics, Ideality factor, Inhomogeneity, Thermionic emission.