Silicon-based Blocked Impurity Band Infrared Detectors For Space Detection

Blocked impurity band (BIB) detectors are the state-of-the-art choice for highly sensitive detection from mid-infrared to far-infrared radiation. In this the-sis, we mainly focus on the device physics, fabrication and optoelectronic charac-teristics of BIB detectors. The main achievements are as follows:1. A device model for the figures of merit of BIB detectors has been built up. The carrier concentration, electric field and photocurrent distribution have been studied based on one of our BIB test devices. The responsivity, gain, excess noise factor and detectivity of the BIB device are calculated as functions of the applied bias and the concentration of residual acceptors. This study offers a potential guidance for further works on BIB designing and optimization.2. Selective ion-implanted Si:P BIB detectors in lateral architecture have been fabricated. These detectors exhibit good blocking characteristics with low dark current density less than 10-4 A/cm2. Linear blackbody response has been observed at small bias voltage (1 V) and cryogenic temperature (5.5 K) with the peak responsivity of 0.8 A/W. The photocurrent spectra show peak response at 27.3 um and extend to 40 um. Several additional sharp peaks and valleys superimposed on the broadband response curve are designated to association with the impurity transitions and the silicon phonon absorption processes.3. Epitaxial Si:P BIB detectors have been fabricated. The bottom contact was epitaxially grown instead of utilizing ion-implantation to improve the quality of epitaxial stack. The photocurrent spectra and dark current of the detectors have been observed. The spectral response extends from 2.5 to 40 um. The origin of dark current at small bias have been studied at cryogenic temperature. It is found that the shield of cryostat is the source of the background infrared light which hits the detectors to produce the dominant dark current at this regime. The detectors attain a peak responsivity of 20.1 A/W and peak detectivity of 5.3 x 1013 cm·Hz1/2·W-1 at 27.5 μm (below a flux of 1013 ph·cm-2·s-1). A calculation of the concentration of residual acceptors has been made by using the breakdown voltage shift under positive and negative bias.4. The existence of an interfacial barrier in BIB detectors has been demon-strated using temperature-dependent dark currents and corresponding the-oretical calculations. A dual-excitation model, including the direct excita-tion over the full barrier and excitation to the band minimum with sub-sequent tunneling into the blocking layer, is proposed to explain the ex-tended photoresponse and the redshift of the threshold frequency. A con-cept of extended-mode detection is developed to realize some selective pho-toresponse with an engineered doping scheme. The tunneling and thermal emission properties of the extended mode have been investigated. The ef-fects of the interfacial barrier on the photoresponse and detectivity of BIB detectors have been studied. It is found that the calculated photoresponse is in good agreement with experimental data when taking the effects of the interfacial barrier into account. This study provides a better understanding of the photoresponse mechanism in BIB detectors and opens the possibility of extending the response to lower frequencies.