Trap parameters in the infrared InAsSb absorber found by capacitance and noise measurements

Abstract

We reported experimentally determined trap parameters for the narrow-gap InAs 1−x Sb x material with the ternary composition x=0.18. The deep level transient spectroscopy supported by the low frequency noise spectroscopy were used to study traps in the mid-wavelength infrared (IR) photodetector with the InAs 1−x Sb x absorber. The trap levels within the bandgap, theirs capture cross-sections and trap concentration were found. Experimentally obtained parameters are consistent with calculated values reported in the literature. The trap levels E t =140-145 meV and E t =45 meV, with respect to the valence band edge, are the most important for IR detectors because levels seem to be pinned to the valence band edge. It means that they are insensitive to composition x of the InAs 1−x Sb x alloy. Consequently, for bulk detectors, each level can lie around the middle of the bandgap and can become an efficient generation-recombination center which degrades the minority carrier lifetime in the mid-wavelength (trap level 140-145 meV) or long-wavelength (trap level 45 meV) IR devices based on the InAs 1−x Sb x material. The levels can be also important for the emerging IR material, i.e. superlattice InAs/InAs 1−x Sb x , where the midgap states can be also introduced by traps located in the InAs 1−x Sb x ternary alloy.

Uncooled mid-wavelength InAsSb/AlAsSb heterojunction photodetectors

“…The E t2 trap is attributed to a cation vacancy (V In ) present in the absorber. 23 An In atom displaced to an interstitial site, generating a nearby negatively charged In vacancy, giving rise to a Frenkel defect (a vacancy-interstitial pair). The minority carriers of holes trapped in the E t2 trap can escape into the valence band edge with E t2 − EV = 46 meV and then reach the p + -InAsSb top contact layer at room temperature under an applied reverse bias because the average thermal energy of 3kBT/2 (≈40 meV) is comparable to the trapping potential energy.…”

Transimpedance Amplifier for Noise Measurements in Low-Resistance IR Photodetectors

“…Noise measurements can be extremely useful in the characterization of electronic devices, since a proper interpretation of the measured noise spectra can provide information on their quality and reliability [1][2][3][4][5]. In the case of sensor devices such as photodetectors, reliable measurements of their current noise characteristics are needed to assess the value of fundamental parameters connected with their responsivity and noise [6,7].…”

Metrology and Measurement Systems

“…Instrumentation for a low frequency noise measurements (LFNM) is a tool used to characterize a wide spectrum of devices [1]. It is applied in many technologies, e.g., semiconductors [2,3], microelectronic materials [4][5][6][7][8][9][10], electro-chemical devices [11], photodetectors [12][13][14][15][16][17][18], as well as other materials [19][20][21]. In this research, some special amplifiers (ultra-low noise amplifier -ULNA) are widely used.…”