Low-frequency noise and performance of GaN p-n junction photodetectors

Abstract

We report on low-frequency noise characteristics of visible-blind GaN p-n junction photodetectors. Carrier hopping through defect states in the space charge region, believed to be associated with dislocations, is identified as the main mechanism responsible for the dark conductivity of the photodiodes. Under reverse bias, the dark current noise has the 1/f character and obeys the Hooge relation with α≈3. Under forward bias, we observe generation-recombination noise related to a trap level with the activation energy of 0.49 eV. Under illumination, detectivity is found to be shot noise limited. The noise equivalent power of a 200×200 μm2 photodetector is estimated at 6.6×10−15 W/Hz1/2 at a bias of −3 V.

Low Frequency Noise in n-GaN with High Electron Mobility

“…This value is two orders of magnitude smaller than values of ␣ in n-GaN reported earlier. 4,5,7,8 Nevertheless, even this relatively low value of ␣ is overestimated for two reasons.…”

“…First estimates of the low-frequency noise level in n-GaN were made using visible-blind GaN p-n junction photodetectors. 4,5 The estimated ␣ value was very high (␣ Ϸ3). This value is comparable with the values of ␣ for such disordered materials as conducting polymers.…”

Generation Recombination Noise in GaN Photoconducting Detectors

“…6 and in GaN p-n junctions operating in the forward bias, grown by MOCVD, and studied used techniques similar to those described in this paper. 15 From the relation τ = 1/v th Sn, where v th is the thermal velocity of electrons, we have calculated the capture cross-section to be S= 2x10 -19 cm 2 , which indicates that the trap is a coulombic center. However, we believe that measurements above 300K are necessary to observe the sharp decrease in τ and A with temperature, as the Fermi-level crosses the trap level.…”

“…It has also been used to characterize the performance of GaN p-n junctions. 15 To the best of our knowledge, this is the first report of using noise measurements to study deep levels in GaN photoconductors.…”

Influence of Carbon Doping on the Photoconductivity in GaN Layers

“…SiC [5]. However, the performance of GaN-detectors in the UV-region critically depends on the quality of the layers and interfaces [6], and, in particular, on the density of deep defect states [7 to 9]. In this work the impact of deep levels which are unintentionally induced by carbon doping on the UV responsivity of the films is investigated.…”