Abstract
A variety of new types of detectors based on wide bandgap materials have been developed for soft X-ray spectroscopy applications(e.g. GaAs, SiC, diamond). In this report we describe the spectroscopicperformance of a simple p-i-n diode fabricated on AlGaAs. The energyresponse of the diode, operating in photon counting mode, at roomtemperature has been investigated using fluorescence from a number of highpurity materials. X-ray spectra over the energy range 5 keV–25 keV showthis type of diode can be used for spectroscopy with promising energyresolution ( ∼ 1.3 keV) at 30°C and excellent linearity.
Highlights
A variety of new types of detectors based on wide band gap materials have been developed for soft X-ray spectroscopy applications (e.g. GaAs, SiC, diamond)
X-ray spectra over the energy range 5 keV–25 keV show this type of diode can be used for spectroscopy with promising energy resolution (∼ 1.3 keV) at 30◦C and excellent linearity
In a number of recent papers we have shown that AlGaAs detectors have many of the attributes, required to survive in relatively harsh environments while offering spectroscopic photon counting imaging
Summary
2.1 Fabrication Circular mesa Al0.8Ga0.2As diodes of radii 25, 50, 100 and 200 μm were fabricated by photolithography from wafers grown on GaAs n+ substrates by molecular beam epitaxy at the National Centre for III-V Technologies, University of Sheffield, U.K. [10]. 2.1 Fabrication Circular mesa Al0.8Ga0.2As diodes of radii 25, 50, 100 and 200 μm were fabricated by photolithography from wafers grown on GaAs n+ substrates by molecular beam epitaxy at the National Centre for III-V Technologies, University of Sheffield, U.K. Each device had an Au/Zn/Au ohmic contact (annealed at 360◦C) to the top p− GaAs layer. In/Ge/Au alloy was deposited on the back n+ substrate and annealed at 420◦C to provide the ohmic n− metal contact. The capacitance of the 100 μm radius diodes was 5 pC for reverse bias voltages > 5 V. Full depletion of the device was achieved for bias voltages > 5 V. An operating bias voltage of 10 V was chosen to ensure full depletion but to keep the leakage current below 0.1 nA
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