Jiang Ruo-Lian

Au/Pt/InGaN/GaN Heterostructure Schottky Prototype Solar Cell

A patterned Au/Pt/In0.2Ga0.8N/GaN heterostructure Schottky prototype solar cell is fabricated. The forward current-voltage characteristics indicate that thermionic emission is a dominant current transport mechanism at the Pt/InGaN interface in our fabricated cell. The Schottky solar cell has an open-circuit voltage of 0.91 V, short-circuit current density of 7mA/cm2, and fill factor of 0.45 when illuminated by a Xe lamp with a power density of 300 mW/cm2. It exhibits a higher short-circuit current density of 30 mA/cm2 and an external quantum efficiency of over 25% when illuminated by a 20-mW-power He-Cd laser.

Photoresponse of the In0.3Ga0.7N metal–insulator–semiconductor photodetectors

In 0.3Ga 0.7N metal–insulator–semiconductor (MIS) and metal–semiconductor (MS) surface barrier photodetectors have been fabricated. The In0.3Ga0.7N epilayers were grown on sapphire by metalorganic chemical vapour deposition (MOCVD). The photoresponse and reverse current–voltage characteristics of the In0.3Ga0.7N MIS and MS photodetectors were measured. A best zero bias responsivity of 0.18 A/W at 450 nm is obtained for the In0.3Ga0.7N MIS photodetector with 10 nm Si3N4 insulator layer, which is more than ten times higher than the In0.3Ga0.7N MS pho-todetector. The reason is attributed to the decrease of the interface states and increase of surface barrier height by the inserted insulator. The influence of the thickness of the Si3N4 insulator layer on the photoresponsivity of the MIS photodetector is also discussed.

High-Reflectivity AlGaN/AlN Distributed Bragg Reflector in Ultraviolet Region

Thirty-pair Al0.3Ga0.7N/AlN distributed Bragg reflectors centred at 320 nm are designed and grown on sapphire substrates by metalorganic chemical vapour deposition. No cracks are observed in the main area of the 2-inch wafer except for about 4 mm margin under an optical microscope. Regular stack of alternating layers is shown by scanning electron microscopy. Clear two-dimensional growth steps and very low surface roughness are shown by atomic force microscopy (AFM). Well-defined periodicity is shown by high resolution x-ray diffraction. High reflectivity of 93% at 313 nm with a bandwidth of 13 nm is obtained.

Demonstration of GaN/InGaN Light Emitting Diodes on (100) β-Ga2O3 Substrates by Metalorganic Chemical Vapour Deposition

The growth and fabrication of GaN/InGaN multiple quantum well (MQW) light emitting diodes ( LEDs) on ( 100) beta-Ga2O3 single crystal substrates by metal-organic chemical vapour deposition (MOCVD) technique are reported. x-ray diffraction (XRD) theta-2 theta. scan spectroscopy is carried out on the GaN buffer layer grown on a ( 100) beta-Ga2O3 substrate. The spectrum presents several sharp peaks corresponding to the ( 100) beta-Ga2O3 and ( 004) GaN. High-quality ( 0002) GaN material is obtained. The emission characteristics of the GaN/InGaN MQW LED are measurement. The first green LED on beta-Ga2O3 with vertical current injection is demonstrated.

Interfacial Properties of AlN/Si (111) Grown by Metal-Organic Chemical Vapour Deposition

We have studied the interfacial structures of AlN/Si (111) grown by metal-organic chemical vapour deposition. X-ray photoelectron spectroscopy and Auger electron spectroscopy were used to analyse the components and chemical structures of AlN/Si (111). The results indicated that a mix-crystal transition region, approximately 12nm, was present between the AlN film and the Si substrate and it was composed of AlN and Si3N4. After analysis we found that the existence of Si3N4 could not be avoided in the AlN/Si (111) interface because of strong diffusion at 1070°C. Even in AlN layer Si-N bonds, Si-Si bonds can be found.

Surface field effect of polyaniline film

Abstract The conducting polymer PAn surface field effect transistor in which a PAn film acts as the semiconductor layer, two Au electrodes separated from each other by 20 μm are utilized as the source and the drain, a Si wafer serves as the gate and a thermally grown SiO2 film is used as the gate insulator layer was fabricated. The obvious surface field effect of PAn film has been observed and the characteristics of the PAn surface field effect transistor has been analized.

Investigation into the Energy Band Diagram and Charge Distribution in AlGaN/GaN Double Heterostructures by Self-Consistent Poisson–Schrödinger Calculations

The energy band diagram and charge distribution of the unintentional doped AlGaN/GaN/AlGaN/GaN double heterostructure were obtained by self-consistent Poisson–Schrodinger calculations. The severe band tilting and high two-dimensional electron gas (2DEG) density mainly attribute to the large internal polarization intensity, which is close to a linear function of Al composition. The influence of Al composition is investigated. The results show that band tilting enlarges and 2DEG gains with Al composition, and two-dimensional hole gas occurs when Al composition reaches a certain extent. The influence of Al composition and two-dimensional hole gas (2DHG) on devices is discussed.

The structure of GexSi1−x/Si strained layer superlattices and heterostructures

Abstract A series ofGeSi/Si strained layer heterostructures grown by rapid radiant heating, very low pressure chemical vapor deposition (RRH/VLP-CVD) on a Si(100) substrate have been studied for the first time. The resultsof XPS and AES studies indicate that the epilayer is a pure GeSi alloy with a homogeneous composition and binding energy values are the same as those of bulk Si and Ge, respectively. The XRD spectra show that the epilayer is a high-quality single crystal with a lattice plane spacing different from that of the bulk GeSi alloy predicted by Vegards law and from that measured from polycrystalline diffraction. This means that the epilayer is a strained film. The RRH/VLP-CVD method has been developed to growGe x Si 1−x /Si superattices. The results of XTEM, XRD and Raman measurements show a well-defined periodic structure with strain in both the alloy sublayers and the Si sublayers. This means a high-quality strained layer superlattice has been obtained.

Photocurrent properties of high-sensitivity GaN ultraviolet photodetectors

GaN epilayers were grown on sapphire substrates by metal-organic chemical vapour deposition. Metal-semiconductor-metal photoconductive detectors were fabricated using this material. The photocurrent properties of the detectors were measured and analysed. The spectrum response shows a high sensitivity in the wavelength region from 330 to 360nm, with a peak at 358nm and a sharp cutoff near 360nm. The maximum responsivities at 358nm were 700A/W (2V) and 7000A/W (30V). The relationship between responsivity and bias indicates that the responsivity increases linearly with bias until 30V. The influence of the spacing between two electrodes on the detector responsivity was also studied.

Photocurrent Properties of the AlGaN/GaN/AlGaN Multilayer Structure on Si

Al0.2Ga0.8N/GaN/Al0.2Ga0.8N multilayer structures and GaN monolayer structures with AlN as the buffer layers were grown on Si substrates by metal-organic chemical vapour deposition. The photocurrent responses of these structures were measured and analysed. The multilayer structures showed a high response in a narrow range of wavelengths. The peak wavelength is located at 365 nm at which the responsivity is as high as 24 A/W under 5.5 V bias; this is much higher than the GaN monolayer structure. This high responsivity results mainly from the high polarization electric field in the GaN layer of the Al0.2Ga0.8N/GaN/Al0.2Ga0.8N heterostructure.