Epitaxial InGaAsP/InP photodiode for registration of InP scintillation

Abstract

Operation of semiconductor scintillators requires optically-tight integration of the photoreceiver system on the surface of the scintillator slab. We have implemented an efficient and fast quaternary InGaAsP pin photodiode, epitaxially grown upon the surface of an InP scintillator wafer and sensitive to InP luminescence. The diode is characterized by an extremely low room-temperature dark current, about 1 nA/cm2 at the reverse bias of 2 V. The low leakage makes possible a sensitive readout circuitry even though the diode has a large area (1 mm/times1 mm) and therefore large capacitance (50 pF). Results of electrical, optical and radiation testing of the diodes are presented. Detection of individual \alpha-particles and \gamma-photons is demonstrated.Comment: 16 pages, 11 figure

Semiconductor Scintillator for Three‐Dimensional Array of Radiation Detectors

“…In the case of such a perfect scintillator, the value of twosided detection is not only that it doubles the overall number of photons collected, but it also provides the position identification not limited to the vertical dimension of the pixel. One can have a thick pixel and still resolve the vertical position from the pre-calibrated ratio (10).…”

“…In collaboration with Sarnoff Corporation, our group has achieved substantial progress with epitaxial photodetectors on InP scintillator body, implemented as ultra-low leakage pin diodes based on quaternary InGaAsP materials. 10 These material layers of 1.24 eV bandgap are grown epitaxially on lattice-matched InP scintillator body and are sensitive to InP scintillation at the wavelength of 0.92 μιη (Αν = 1.35 eV). The epitaxial diode provides nearly perfect registration efficiency of photons that have reached the heterointerface.…”

Low-Power Amplifier for Readout Interface of Semiconductor Scintillator

“…In high-quality InP, a scintillation photon is not completely lost in an act of interband absorption, since a newly created minority carrier generates upon recombination a new scintillation photon in a random direction [4], [6]. Recent progress towards realization of the InP scintillator is described in [7]. An important advantage of the semiconductor scintillator is the ability to integrate an epitaxial photodiode [7] on the scintillator body, ensuring nearly perfect registration of the scintillation photons.…”

“…Recent progress towards realization of the InP scintillator is described in [7]. An important advantage of the semiconductor scintillator is the ability to integrate an epitaxial photodiode [7] on the scintillator body, ensuring nearly perfect registration of the scintillation photons. Based on the Compton telescope technique [8], a three-dimensional array [4] of semiconductor scintillators (illustrated in Fig.…”

“…In the proposed semiconductor scintillator array, the size of the single pixel epitaxial photodiode is 1 mm 1 mm. A large area of the photodiode gives rise to a large capacitance, measured at 50 pF [7]. The large diode capacitance leads to a higher noise figure and a potential instability in the amplifier design.…”