[7] ZHU L G, KUBERA B, FAI MAK K, et al. Effect of surface states on terahertz emission from the Bi₂Se₃ surface[J]. Scientific Reports, 5, 10308(2015).

[8] HUANG Y Y, ZHU L P, YAO Z H, et al. Terahertz surface emission from layered MoS₂ crystal: competition between surface optical rectification and surface photocurrent surge[J]. The Journal of Physical Chemistry C, 122, 481-488(2018).

[9] ADOMAVIČIUS R, URBANOWICZ A, MOLIS G, et al. Terahertz emission from p-InAs due to the instantaneous polarization[J]. Applied Physics Letters, 85, 2463-2465(2004).

[10] MENDIS R, SMITH M L, BIGNELL L J, et al. Strong terahertz emission from (100) p-type InAs[J]. Journal of Applied Physics, 98, 126104(2005).

[11] SHEN Y C, UPADHYA P C, LINFIELD E H, et al. Ultrabroadband terahertz radiation from low-temperature-grown GaAs photoconductive emitters[J]. Applied Physics Letters, 83, 3117-3119(2003).

[12] ANTSYGIN V D, NIKOLAEV N A. Efficiency of generation of terahertz radiation in GaAs, InAs, and InSb crystals[J]. Optoelectronics, Instrumentation and Data Processing, 47, 338-344(2011).

[13] LI X B, HUANG W K, LV Y Y, et al. Experimental observation of topological edge states at the surface step edge of the topological insulator ZrTe₅[J]. Physical Review Letters, 116, 176803(2016).

[14] MALEVICH V L, ADOMAVIČIUS R, KROTKUS A. THz emission from semiconductor surfaces[J]. Comptes Rendus Physique, 9, 130-141(2008).

[15] ZHANG X C, HU B B, DARROW J T, et al. Generation of femtosecond electromagnetic pulses from semiconductor surfaces[J]. Applied Physics Letter, 56, 1011-1013(1990).

[16] APOSTOLOPOULOS V, BARNES M E. THz emitters based on the photo-Dember effect[J]. Journal of Physics D:Applied Physics, 47, 374002(2014).

[17] HU B B, ZHANG X C, AUSTON D H. Terahertz radiation induced by subband-gap femtosecond optical excitation of GaAs[J]. Physical Review Letters, 67, 2709-2712(1991).

[18] JOHNSTON M B, WHITTAKER D M, CORCHIA A, et al. Simulation of terahertz generation at semiconductor surfaces[J]. Physical Review B, 65, 165301(2002).

[19] NAKAJIMA M, HANGYO M, OHTA M, et al. Polarity reversal of terahertz waves radiated from semi-insulating InP surfaces induced by temperature[J]. Physical Review B, 67, 195308(2003).

[20] FANG Z J, WANG H T, WU X J, et al. Nonlinear terahertz emission in the three-dimensional topological insulator Bi₂Te₃ by terahertz emission spectroscopy[J]. Applied Physics Letters, 115, 191102(2019).

[21] LIU K, XU J Z, YUAN T, et al. Terahertz radiation from InAs induced by carrier diffusion and drift[J]. Physical Review B, 73, 155330(2006).

[22] GU P, TANI M, KONO S, et al. Study of terahertz radiation from InAs and InSb[J]. Journal of Applied Physics, 91, 5533-5537(2002).

[23] ASCÁZUBI R, SHNEIDER C, WILKE I, et al. Enhanced terahertz emission from impurity compensated GaSb[J]. Physical Review B, 72, 045328(2005).